Georgia Medicare Secondary Payer (MSP) Rules: A Complete Guide

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The Medicare Secondary Payer (MSP) rules under Section 1862(b) of the Social Security Act (42 USC 1395y(b)) and 42 CFR Part 411 are the framework that determines when Medicare pays primary versus secondary to other coverage. The framework affects every interaction between Medicare and an employer Group Health Plan (GHP), workers' compensation, no-fault auto insurance, liability insurance, Federal Employee Health Benefits (FEHB), TRICARE, VA coverage, and Medicaid. MSP rules drive the Part B Late Enrollment Penalty framework (which beneficiaries can delay Part B without LEP and which cannot), provider billing decisions (who pays first and what each payer owes), Medicaid dual-eligible coordination (Medicare always primary, Medicaid always payer of last resort), and the Section 111 mandatory reporting requirements that govern how employers and insurers report coverage to CMS. :::

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• The working aged 20-employee rule (§1862(b)(1)(A)) makes large-employer GHP primary to Medicare for seniors with coverage based on active employment; only this coverage qualifies for the Part B Working Aged GHP Special Enrollment Period.
• The disability 100-employee rule (§1862(b)(1)(B)) applies the same framework for SSDI beneficiaries under 65, with a higher 100-employee threshold.
• The ESRD 30-month coordination rule (§1862(b)(1)(C)) makes any employer GHP primary regardless of employer size for the first 30 months of Medicare ESRD entitlement.
• COBRA is not coverage based on current employment and does NOT extend GHP SEP eligibility; the 8-month SEP clock starts when active employment ends, not when COBRA ends.
• Medicaid is always payer of last resort under §1902(a)(25); providers cannot bill QMB enrollees for Medicare cost-sharing under §1902(n)(3)(B). :::

The MSP framework was created by the Tax Equity and Fiscal Responsibility Act of 1982 (TEFRA, Public Law 97-248) as a cost-saving measure designed to shift Medicare from primary to secondary payer status in many contexts where other coverage exists. The Omnibus Budget Reconciliation Act of 1986 (OBRA 1986, Public Law 99-509) extended MSP to disability beneficiaries under age 65. Subsequent legislation including the Medicare Prescription Drug, Improvement, and Modernization Act of 2003 (MMA, Public Law 108-173), the Medicare, Medicaid, and SCHIP Extension Act of 2007 (MMSEA, Public Law 110-173, which added Section 111 mandatory reporting), the 21st Century Cures Act of 2016, and the Beneficiary Enrollment Notification and Eligibility Simplification (BENES) Act of 2020 has refined and expanded the framework. The most recent regulatory update is at 89 Federal Register 17,752, which made significant changes to Section 111 mandatory reporting and conditional payment recovery procedures.

Misunderstanding the MSP rules is one of the most common causes of avoidable Medicare problems in Georgia. Beneficiaries working for small employers (fewer than 20 employees) face the small-employer trap: they assume any employer coverage allows them to delay Part B enrollment, but only large-employer (20+) GHP coverage qualifies for the Working Aged Special Enrollment Period under Section 1838(g). Retirees with COBRA continuation coverage face the COBRA trap: COBRA is not coverage based on current employment, so it does not extend MSP-primary status for the GHP. Workers' compensation beneficiaries face the conditional payment recovery process when settlements include compensation for medical care Medicare paid for. ESRD beneficiaries face the 30-month coordination period during which the employer GHP is primary regardless of employer size. Each of these scenarios is governed by specific MSP provisions that this guide explains in detail.

This guide gives Georgia families the complete picture: the federal MSP framework (Section 1862(b) of the SSA, 42 CFR Part 411 Subparts F and G, the 2024 final regulations update); the four core MSP rules (working aged 20-employee, disability 100-employee, ESRD 30-month coordination, workers' comp and liability); Section 111 mandatory reporting requirements; conditional payment recovery and Medicare Set-Aside Arrangements (MSAs); how MSP affects the Part B Late Enrollment Penalty and the Working Aged GHP SEP; the COBRA trap; FEHB, TRICARE, and VA coordination; Medicaid as payer of last resort; common provider improper billing scenarios; fifteen common mistakes; and six worked examples for typical Georgia MSP scenarios.

By Brevy Care Team · Last verified May 13, 2026

The Federal MSP Framework

The Medicare Secondary Payer rules are codified at Section 1862(b) of the Social Security Act (42 USC 1395y(b)) and implemented in 42 CFR Part 411. The statutory framework was originally adopted by the Tax Equity and Fiscal Responsibility Act of 1982, which made Medicare secondary to certain group health plans for working aged beneficiaries. The 1986 OBRA extended the framework to disability beneficiaries, and subsequent legislation expanded MSP to ESRD beneficiaries, refined workers' compensation coordination, added Section 111 mandatory reporting, and updated administrative procedures. The most recent major update is the 2024 final regulations at 89 Federal Register 17,752, which strengthened Section 111 reporting enforcement and clarified conditional payment recovery procedures.

The core principle of MSP is simple: in certain defined contexts, Medicare pays after other coverage rather than before. The "other coverage" categories are specifically enumerated in Section 1862(b) and 42 CFR Part 411. Medicare is secondary to: (1) group health plans based on current employment in specified contexts; (2) workers' compensation insurance; (3) no-fault auto insurance; (4) liability insurance (including auto, slip-and-fall, medical malpractice, product liability, and similar); (5) the Federal Black Lung Program for related conditions. In all other contexts, Medicare is primary. The MSP framework is exhaustive: if a coverage category is not listed in Section 1862(b), Medicare is primary.

The MSP framework is operationally complex because it requires real-time identification of primary-payer status, which depends on employment circumstances, employer size, age, disability status, ESRD status, accident circumstances, and other factors that change over time. CMS uses Section 111 mandatory reporting (added by MMSEA 2007) to receive information from employers and insurers, the Medicare Beneficiary Database, the Common Working File, and the Medicare Coordination of Benefits Contractor to track MSP status. The Medicare Secondary Payer Recovery Center processes disputes and conditional payment recovery.

Rule 1: Working Aged 20-Employee Rule Under Section 1862(b)(1)(A)

The most important MSP rule for Georgia working seniors is the working aged 20-employee rule under Section 1862(b)(1)(A). The rule provides that if a Medicare-entitled beneficiary age 65 or older has coverage from an employer Group Health Plan based on the beneficiary's own or their spouse's current employment with an employer that has 20 or more employees, the GHP is the primary payer and Medicare is the secondary payer.

The "20 or more employees" threshold is determined by counting employees nationwide, not just at the beneficiary's worksite or in Georgia. A Georgia-based law firm with 12 local employees but with 25 total employees (including a New York office) has 25 employees for MSP purposes and meets the threshold. The employer size determination is made by the GHP plan sponsor for purposes of Section 111 reporting and is reflected in the GHP's plan documents.

The "current employment" requirement means active employment, not retirement. Retiree coverage, even if provided by the former employer and similar to the active-employee GHP, does NOT qualify for primary-payer status under Section 1862(b)(1)(A). The retiree coverage is post-employment and is not "based on current employment." Beneficiaries with retiree GHP coverage are NOT in MSP-primary status; Medicare is primary, and the retiree coverage is secondary or coordinates as excess coverage.

The "GHP" definition under MSP includes any group health plan that provides medical care to employees, retirees, or their families. The plan must be a "group" plan (covering multiple employees) and must provide "medical care" (broadly defined). Most employer-sponsored health plans qualify. Self-insured plans (where the employer pays claims directly rather than through an insurance carrier) qualify if they meet the group-plan requirements. Multiple-employer plans (MEPs) qualify based on the combined employment of all participating employers.

The Section 1862(b)(1)(A) rule has critical implications for the Part B Late Enrollment Penalty. Beneficiaries with MSP-primary GHP coverage qualify for the Working Aged Group Health Plan Special Enrollment Period under Section 1838(g) of the SSA. The SEP allows the beneficiary to delay Part B enrollment without LEP during active employment, with an 8-month window to enroll after active employment ends. Beneficiaries without MSP-primary GHP coverage (small-employer GHP, retiree coverage, COBRA) do NOT qualify for the GHP SEP and must enroll in Part B during the IEP at age 65 to avoid LEP.

Rule 2: Disability 100-Employee Rule Under Section 1862(b)(1)(B)

For Medicare beneficiaries under age 65 who are entitled to Medicare based on Social Security Disability Insurance (SSDI), a different MSP rule applies. Section 1862(b)(1)(B) of the SSA provides that if the SSDI beneficiary or a family member has coverage from an employer GHP based on current employment with an employer that has 100 or more employees, the GHP is the primary payer and Medicare is secondary.

The 100-employee threshold is higher than the working aged 20-employee threshold because Congress wanted to limit the cost-shifting burden on smaller employers for disabled-employee coverage. The threshold is determined by counting employees nationwide for the employer that sponsors the GHP. The threshold is also for the employer, not for the individual SSDI beneficiary's job.

Common scenarios where the disability 100-employee rule applies:

A 50-year-old SSDI beneficiary's spouse works at a 200-employee firm. The spouse's family GHP covers the SSDI beneficiary. The GHP is primary under Section 1862(b)(1)(B). Medicare is secondary.

A 60-year-old SSDI beneficiary continues working at a 150-employee firm during a trial work period under Section 222(c) of the SSA. The firm's GHP covers the SSDI beneficiary. The GHP is primary under Section 1862(b)(1)(B).

An adult child SSDI beneficiary is covered under their working parent's family GHP at a 500-employee firm. The GHP is primary under Section 1862(b)(1)(B).

For SSDI beneficiaries with GHP coverage from employers with fewer than 100 employees, Medicare is primary even during active employment. The smaller-employer GHP is secondary or excess. This affects Part B premium responsibility, GHP enrollment-period timing, and provider billing.

Rule 3: ESRD 30-Month Coordination Period Under Section 1862(b)(1)(C)

For Medicare beneficiaries entitled based on End-Stage Renal Disease (ESRD), Section 1862(b)(1)(C) of the SSA establishes a 30-month coordination period during which an employer Group Health Plan is primary regardless of employer size. The coordination period begins with the month Medicare ESRD entitlement begins (typically the fourth month of dialysis, with earlier options for self-care training or kidney transplant) and ends 30 months later.

The ESRD rule is unique because it has no employer-size threshold. It applies to all GHP coverage, regardless of whether the employer has 20+ employees (working aged threshold), 100+ employees (disability threshold), or fewer. A 50-year-old ESRD beneficiary with GHP coverage from a 5-employee small business has primary-payer GHP for the first 30 months of Medicare ESRD entitlement under Section 1862(b)(1)(C). After 30 months, Medicare becomes primary regardless of continued employment.

The 30-month coordination period is calculated month-by-month from the start of Medicare ESRD entitlement, not from the start of dialysis. If dialysis begins in March 2025 and Medicare entitlement begins July 1, 2025 (the fourth month of dialysis under standard ESRD entitlement rules), the 30-month period runs July 2025 through December 2027. Effective January 2028, Medicare becomes primary.

The ESRD rule has significant implications for Georgia kidney patients with employer coverage. During the 30-month period, the GHP pays primary for ESRD-related care including dialysis, transplant evaluation, transplant surgery (when applicable), immunosuppressant medications post-transplant, and related care. Medicare pays secondary, covering deductibles, coinsurance, and gaps. After 30 months, the GHP becomes secondary and Medicare pays primary.

Rule 4: Workers' Compensation, No-Fault Auto, and Liability Coordination

Section 1862(b)(2) of the SSA makes Medicare secondary to workers' compensation insurance, no-fault auto insurance, and liability insurance for treatment of injuries or illnesses covered by those payers. The rule is unconditional and not subject to employer-size thresholds: Medicare is always secondary to these payers in their respective contexts.

Workers' compensation: Medicare is secondary to workers' compensation for treatment of work-related injuries or illnesses. Georgia workers' compensation is administered by the Georgia State Board of Workers' Compensation under O.C.G.A. Title 34 Chapter 9. When a Georgia worker (regardless of age or Medicare status) is injured on the job, the employer's workers' comp insurer is primary for medical care related to the injury. The workers' comp insurer authorizes treatment through a panel of physicians selected by the employer; the worker has limited choice of provider.

For Medicare-entitled workers with active workers' comp claims, Medicare pays nothing on the work-related care during the active claim period. If workers' comp denies the claim, delays processing, or the claim is in dispute, Medicare may pay conditional benefits to ensure the beneficiary receives needed care. When workers' comp eventually pays or settles, CMS recovers the conditional payments from the workers' comp proceeds through the Medicare Secondary Payer Recovery Center.

No-fault auto insurance: Medicare is secondary to no-fault auto insurance for injuries sustained in covered auto accidents during the no-fault primary period (which varies by state). Georgia is not a traditional no-fault state (Georgia is an at-fault tort state with personal injury protection or PIP as an optional add-on coverage), so this rule applies in limited Georgia contexts.

Liability insurance: Medicare is secondary to liability insurance for injuries arising from third-party liability situations, including auto accidents (where another driver is at fault), slip-and-fall accidents, medical malpractice, product liability, dog bites, and any other liability claim. When a Georgia Medicare beneficiary receives a liability settlement or judgment that compensates for medical treatment Medicare paid for, CMS can recover the conditional payments through the Medicare Secondary Payer Recovery Center.

Section 111 Mandatory Reporting Under MMSEA 2007

Section 111 of the Medicare, Medicaid, and SCHIP Extension Act of 2007 (Public Law 110-173) requires GHPs, liability insurers, no-fault auto insurers, and workers' compensation entities to report information to CMS that helps CMS identify situations where Medicare should be secondary. The reporting is mandatory and enforced with substantial financial penalties for non-compliance.

Section 111 reporting feeds CMS's MSP determination process. CMS uses the reports to identify primary-payer coverage and prevent Medicare from paying primary when other coverage should be primary. The reports include: (1) for GHPs, the identity of covered employees and dependents, the employer size, the effective dates of coverage, and the type of plan; (2) for liability and no-fault insurers, the identity of claimants, the date of the underlying accident or injury, and the settlement or judgment amount; (3) for workers' comp insurers, the identity of injured workers, the date of injury, and benefit details.

The Section 111 framework operates through Responsible Reporting Entities (RREs), which are typically the employer, the insurer, or a third-party administrator. RREs submit quarterly reports to CMS through a secure web portal. The 2024 final regulations at 89 Federal Register 17,752 enhanced reporting requirements, updated formats, and clarified enforcement procedures.

Beneficiaries can interact with CMS's Section 111 reporting through the Medicare Coordination of Benefits and Recovery Portal, where they can update their coverage information, dispute MSP determinations, and respond to conditional payment recovery demands.

Conditional Payment Recovery and Medicare Set-Aside Arrangements

When CMS determines that Medicare paid primary in a situation where it should have been secondary, CMS issues a conditional payment recovery demand to recover the conditional payments. The recovery process is governed by 42 CFR Part 411 Subpart F and the Medicare Secondary Payer Recovery Center procedures.

Common recovery scenarios:

A Georgia beneficiary receives a $100,000 liability settlement for injuries from a car accident. Medicare paid $30,000 in conditional payments for treatment of those injuries while liability litigation was pending. After the settlement, CMS issues a recovery demand for approximately $30,000 (potentially reduced by procurement costs and other factors). The beneficiary must pay the demand from the settlement proceeds.

A Georgia beneficiary's work-related injury is initially treated under workers' comp, but workers' comp denies the claim or delays processing. Medicare pays conditional benefits. When workers' comp eventually settles or pays, CMS recovers the conditional payments from the workers' comp proceeds.

An employer fails to report Section 111 GHP coverage to CMS. Medicare pays primary for two years before the GHP is discovered. CMS issues a recovery demand to the GHP for the conditional payments plus interest.

For workers' compensation settlements and certain liability settlements that include future medical expenses for the underlying injury, CMS encourages or requires the use of Medicare Set-Aside Arrangements (MSAs). An MSA is a trust or escrow account that holds settlement funds specifically allocated for future Medicare-covered medical expenses related to the underlying injury. The beneficiary spends from the MSA for related medical expenses; Medicare does not pay for related care until the MSA is exhausted.

CMS's review of MSA proposals is voluntary for workers' compensation settlements above certain thresholds and for liability settlements above certain amounts (current thresholds are published in CMS's WCMSA Reference Guide). The CMS Workers' Compensation Review Contractor evaluates the proposed MSA amount and approves, modifies, or rejects the proposal.

The MSA framework is complex and typically requires specialized legal counsel. Georgia beneficiaries facing significant workers' comp or liability settlements should consult an attorney who handles MSP/MSA matters before signing settlement documents. The MSA structure protects Medicare's secondary-payer interest and prevents the beneficiary from settling for too little allocated to future medical care, which would leave Medicare to pay for related care without proper allocation.

How MSP Affects the Part B Late Enrollment Penalty

The MSP framework is the predicate for the Working Aged Group Health Plan Special Enrollment Period under Section 1838(g) of the SSA, which is the most important LEP-avoidance mechanism for beneficiaries working past age 65. The Section 1838(g) SEP applies only to beneficiaries with primary-payer GHP coverage based on current employment.

Under Section 1862(b)(1)(A), primary-payer GHP coverage requires the employer to have 20 or more employees and the coverage to be based on current employment (the beneficiary's or spouse's). A beneficiary working for a large employer (20+) past age 65 with active GHP coverage has primary-payer GHP under MSP. Medicare is secondary. The beneficiary can delay Part B enrollment without LEP under the GHP SEP. When active employment ends, the beneficiary has 8 months to enroll in Part B without LEP.

A beneficiary working for a small employer (fewer than 20 employees) past age 65 with active GHP coverage does NOT have primary-payer GHP under MSP. Medicare is primary even during active employment. The GHP becomes secondary or excess coverage. The beneficiary does NOT qualify for the GHP SEP and must enroll in Part B during the IEP at age 65 to avoid LEP.

This small-employer trap is one of the most common avoidable LEPs in Georgia. Beneficiaries working at small businesses often assume that any employer coverage delays Part B enrollment, but the MSP framework requires the 20-employee threshold for primary-payer status and SEP eligibility. Beneficiaries should confirm employer size with their HR office before relying on the GHP SEP, ideally documented in writing through Form CMS-L564 (Request for Employment Information).

The COBRA MSP Trap

COBRA continuation coverage under the Consolidated Omnibus Budget Reconciliation Act of 1985 is the second most common cause of avoidable Medicare problems in Georgia. The MSP framework treats COBRA as post-employment coverage that does not qualify as "based on current employment" under Section 1862(b)(1)(A). As a result, COBRA does NOT establish MSP-primary status for the GHP.

The COBRA trap has cascading consequences for Medicare-entitled retirees. First, the Working Aged GHP SEP clock starts at the end of active employment, not at the end of COBRA. A beneficiary who takes 18 months of COBRA after retiring at age 65 has burned through 18 of the 8 SEP months and is past the SEP deadline by the time COBRA ends. The beneficiary must wait for the next General Enrollment Period (January 1 through March 31) and faces an LEP for the delayed enrollment.

Second, the beneficiary is responsible for Medicare cost-sharing (Part A deductibles, Part B coinsurance, Part D copays) even while on COBRA, because COBRA is not primary. Medicare is primary; COBRA is secondary or coordinates as excess coverage. Providers should bill Medicare first and COBRA second, with the beneficiary responsible for any uncovered amounts.

Third, COBRA providers may not realize the MSP status and may bill the beneficiary improperly, treating COBRA as primary when in fact it is secondary. The beneficiary may face billing disputes, denied claims, and out-of-pocket costs that should have been covered by proper Medicare coordination.

The COBRA trap is best avoided by enrolling in Part B at the end of active employment, regardless of whether COBRA is available. Beneficiaries who are uncertain about the timing should consult GeorgiaCares SHIP at 1-866-552-4464 before declining Part B enrollment in reliance on COBRA.

FEHB, TRICARE, and VA Coordination

The Federal Employee Health Benefits (FEHB) program coordinates with Medicare in specific ways. For active federal employees, FEHB is primary and Medicare is secondary. For federal retirees who enrolled in both Medicare Part B and FEHB, the coordination depends on whether the retiree maintained Medicare Part B enrollment. FEHB does NOT require Part B enrollment for active employees or retirees, but federal retirees who delay Part B may face the same LEP issues that affect private-sector retirees if they later try to enroll. Federal retirees should consult the Office of Personnel Management before declining Part B.

TRICARE for Life (TFL) is the Medicare wrap coverage for military retirees and their dependents. TFL is unique: it REQUIRES Medicare Part B enrollment to remain effective. A military retiree who fails to enroll in Part B at age 65 loses TFL coverage entirely. Medicare is primary for TFL beneficiaries; TFL is secondary and covers most Medicare cost-sharing. The TFL requirement for Part B is a critical MSP-related rule for the substantial Georgia military retiree population.

Active-duty TRICARE: Active-duty military members and their dependents have TRICARE as their primary coverage. Medicare entitlement is rare during active duty but possible (for example, for spouses age 65 of active-duty military). In those cases, TRICARE is primary and Medicare is secondary.

VA coverage: VA care is delivered through VA facilities under VA rules. VA is not technically a primary or secondary payer in the MSP sense; rather, VA covers care provided by VA facilities or authorized non-VA providers. Medicare covers care provided by non-VA Medicare providers. A veteran enrolled in both VA care and Medicare can use either system, but VA does not "coordinate" with Medicare in the typical payer-coordination sense.

Medicaid as Payer of Last Resort

Under Section 1902(a)(25) of the Social Security Act, Medicaid is always the payer of last resort. Medicare is always primary to Medicaid in dual-eligible contexts. The Coordination of Benefits Agreement (COBA) between Georgia DCH and CMS facilitates the data exchange that allows Medicare to pay primary and Medicaid to pay secondary for dual-eligibles.

For Qualified Medicare Beneficiary (QMB) enrollees and full-dual eligibles: Medicare pays primary; Georgia Medicaid pays the Medicare Part B premium through the State Buy-In and Medicare cost-sharing for QMB enrollees. For full-duals, Medicaid also covers Medicaid-only services (long-term care, dental, vision, etc.) that Medicare does not cover.

For Specified Low-Income Medicare Beneficiary (SLMB) and Qualifying Individual (QI) enrollees: Medicare pays primary; Georgia Medicaid pays only the Medicare Part B premium (not cost-sharing). SLMB and QI beneficiaries are responsible for Medicare cost-sharing themselves.

Provider improper billing is a critical compliance issue under MSP-Medicaid coordination. Under federal law (Section 1902(n)(3)(B) of the SSA) and Georgia DCH policy, providers cannot bill QMB enrollees for Medicare cost-sharing. The provider must accept the Medicare-allowed amount plus the Medicaid cost-sharing payment as payment in full. Beneficiaries facing improper QMB billing can file complaints with DCH Medicaid Member Services at 1-866-211-0950 or with Medicare directly at 1-800-MEDICARE.

Worked Examples for Typical Georgia MSP Scenarios

William 67 Atlanta: large-employer GHP, primary, Part B properly delayed

William continued working past 65 at his Atlanta-based engineering firm, which has approximately 300 employees nationwide across three offices. He turned 65 in May 2024 but did not enroll in Part B at that time. His firm's GHP, a self-insured plan administered by Anthem, is the primary payer under Section 1862(b)(1)(A) of the SSA: the employer has 20 or more employees and the coverage is based on William's current employment. Medicare Part A (which William has automatically because he is collecting Social Security) is secondary.

William properly delayed Part B enrollment under the Working Aged GHP Special Enrollment Period under Section 1838(g). He paid no Part B premium and no LEP during his continued employment from May 2024 through 2027. He documented the GHP coverage by completing Form CMS-L564 (Request for Employment Information), which his HR office signed and which he retained for his records.

When William retires at age 70 in May 2029, his 8-month GHP SEP will run from June 1, 2029 through January 31, 2030. He will enroll in Part B during the SEP without LEP. Coverage will start the first day of the month after enrollment. William is a textbook example of how the MSP framework supports the GHP SEP for beneficiaries with large-employer active GHP coverage.

Maria 66 Savannah: small-employer GHP trap

Maria works at a 12-employee Savannah accounting firm. She turned 65 in September 2024 and assumed her firm's GHP would qualify her for the GHP SEP, allowing her to delay Part B enrollment without LEP. The assumption was incorrect.

Under Section 1862(b)(1)(A), MSP-primary status requires the employer to have 20 or more employees. Maria's firm has 12 employees, below the threshold. Medicare is primary even during her active employment; the small-employer GHP is secondary or excess coverage. The Section 1838(g) GHP SEP does NOT apply to Maria.

Maria did not enroll in Part B at age 65, relying on the small-employer GHP. By 2026 when she finally consulted GeorgiaCares SHIP, she had missed the IEP by approximately 17 months. Her enrollment will be through the next General Enrollment Period (January 2026) with coverage starting February 2026 under BENES Act post-2023 rules. Her delay produces a 10 percent LEP (one full 12-month period). Her 2026 monthly cost is $202.90 + $20.29 = $223.19.

Maria's GHP, having been secondary all along, did pay for some of her care between 2024 and 2026, but providers had to bill Medicare first and were denied (because Maria had no Part B), creating ongoing billing disputes that consumed substantial time and money to resolve. The MSP framework caused both the LEP and the billing complications. Maria's GHP coverage continues, now as secondary to Medicare, but her LEP will follow her permanently.

Robert 62 Macon: SSDI + large-employer disability under Section 1862(b)(1)(B)

Robert is 62, has been receiving SSDI for several years, and has Medicare based on SSDI entitlement. His wife works at a Macon company with 500 employees, and Robert is covered under her family GHP. Under Section 1862(b)(1)(B) of the SSA, the GHP is primary because the employer has 100 or more employees and the coverage is based on the spouse's current employment.

Medicare is secondary for Robert. He pays no Part B LEP and (as a working spouse's covered SSDI beneficiary) qualifies for the Disabled Beneficiary Special Enrollment Period if his wife's employment ends and the GHP coverage based on current employment ends. The 8-month SEP applies.

If Robert's wife worked for a smaller firm (under 100 employees, even if 20 or more), Medicare would be primary and Robert would have needed to maintain active Part B enrollment to avoid LEP. The 100-employee threshold for disability beneficiaries is higher than the 20-employee threshold for working aged because Congress recognized that smaller employers have less capacity to absorb the cost of being primary payer for disabled employees.

Patricia 55 Augusta: ESRD coordination period under Section 1862(b)(1)(C)

Patricia started dialysis in March 2025 in Augusta after kidney failure related to long-standing diabetes. She is 55 and has employer GHP coverage at a 50-employee firm where she works as a paralegal. Patricia is entitled to Medicare based on ESRD effective July 1, 2025 (the fourth month of dialysis under standard ESRD entitlement rules).

Under Section 1862(b)(1)(C), the 30-month ESRD coordination period begins July 2025 and runs through December 2027. During the 30-month period, the employer GHP is primary regardless of employer size. The 50-employee firm size is irrelevant for ESRD; the rule applies to all GHPs.

After December 2027, Medicare becomes primary regardless of Patricia's continued employment status. The employer GHP, if Patricia still has it, becomes secondary.

Patricia enrolls in Part B during her IEP (around the start of ESRD entitlement) to ensure Medicare can pay secondary during the 30-month period and primary thereafter. The MSP framework requires Patricia's Part B enrollment to align with ESRD entitlement; failure to enroll would not extend the 30-month period but would prevent Medicare from paying secondary properly.

Patricia's dialysis treatment, kidney transplant evaluation, eventual kidney transplant (when a match is found), and post-transplant care are all covered primarily by her GHP for the 30-month period, with Medicare paying secondary for deductibles, coinsurance, and gaps.

Charles 70 Columbus: workers' compensation claim

Charles, age 70 in Columbus, sustained a work-related back injury at his part-time job at a local hardware store. He has Medicare Parts A and B. Georgia workers' compensation (his employer's workers' comp insurer) is primary for treatment of the work-related back injury under O.C.G.A. Title 34 Chapter 9 and Section 1862(b) MSP rules. Medicare is secondary.

The workers' comp insurer authorizes Charles's surgery and physical therapy through a panel of physicians selected by the employer. Medicare pays nothing on the work-related care during the active workers' comp claim. However, Charles's regular Medicare-covered care unrelated to the injury (diabetes management, annual physical, prescription medications unrelated to the injury) continues under normal Medicare payer rules.

Two years into the claim, Charles settles with the workers' comp insurer for $150,000, of which $80,000 is allocated for future medical expenses for the back injury. Under MSP rules, the $80,000 is placed in a Medicare Set-Aside Arrangement (MSA). CMS reviews the MSA proposal because Charles is a current Medicare beneficiary and the settlement meets the CMS voluntary review thresholds. CMS approves the proposed MSA amount.

Charles draws from the MSA for back-injury-related care; Medicare does not pay for that care until the MSA is exhausted. Once exhausted, Medicare pays normally subject to standard secondary-payer rules. Without the MSA, CMS could have rejected the settlement allocation and required higher MSA funding, potentially impacting Charles's settlement value.

Susan 68 Athens: COBRA MSP trap

Susan retired from her Athens administrative job at age 65 in 2023. Her firm had 200 employees, so during her active employment she had primary-payer GHP under Section 1862(b)(1)(A). She did not enroll in Part B at age 65, correctly relying on the GHP SEP.

Upon retirement, Susan elected COBRA continuation coverage for 18 months. She believed COBRA would maintain her GHP SEP status and that she could enroll in Part B when COBRA ended without LEP. This was incorrect: COBRA is not coverage based on current employment under Section 1862(b)(1)(A).

Susan's Working Aged GHP SEP started at the end of active employment in 2023 and ran for 8 months through approximately mid-2024. She did not enroll within the SEP window because she was on COBRA and assumed she had until COBRA ended.

Meanwhile, the COBRA insurance was secondary to Medicare under MSP from the moment her active employment ended. Providers who billed COBRA were billed primary in error and had claims denied because Susan had no Part B to bill secondary. Susan accumulated approximately $4,200 in unpaid bills from emergency room visits and specialist consultations during the COBRA period.

When COBRA ended in early 2025, Susan enrolled in Part B through the next GEP. Her delay from the end of her IEP (which had been in 2023) to her actual Part B effective date in 2025 produced a 10 percent LEP. Her 2026 monthly cost is $202.90 + $20.29 = $223.19, plus the residual billing disputes from 2023 through 2025 that took GeorgiaCares assistance and substantial time to resolve. The COBRA MSP trap is among the most damaging in the entire framework and is a frequent topic in SHIP counseling sessions.

Common Mistakes in Georgia MSP Coordination

1. Assuming all employer GHP coverage allows Part B delay. The 20-employee rule (working aged) and 100-employee rule (disability) define which GHP coverage supports the SEP.

2. Assuming COBRA extends MSP status and the GHP SEP. COBRA is post-employment continuation, not coverage based on current employment.

3. Failing to enroll in Part B during the 8-month SEP. Many beneficiaries lose track of the deadline because they assume the SEP runs from the end of any coverage.

4. Not reporting employment changes to CMS via Section 111. Employers are responsible for Section 111 reporting, but beneficiaries should also update CMS through the MSP Recovery Portal.

5. Confusing the 30-month ESRD rule with the working-aged or disability rules. The ESRD rule applies to all GHPs regardless of employer size.

6. Treating workers' comp settlements without considering MSA requirements. CMS recovery for conditional payments and future medical expenses can claw back substantial settlement proceeds.

7. Forgetting that Medicare is secondary to workers' comp. Beneficiaries with work-related injuries should ensure providers bill workers' comp first.

8. Filing claims with Medicare when liability insurance is the proper primary. This causes Medicare conditional payments and later recovery.

9. Assuming retiree coverage is GHP for SEP purposes. Retiree coverage is not "based on current employment" and does not qualify for the GHP SEP.

10. Not appealing employer-size determinations. Beneficiaries can challenge CMS determinations through the MSP Recovery Center.

11. Failing to coordinate Medicaid with Medicare correctly. Medicaid is payer of last resort; Medicare is always primary in dual-eligible contexts.

12. Allowing improper QMB billing. Providers cannot bill QMB enrollees for Medicare cost-sharing under federal and state law.

13. Not understanding TRICARE for Life requires Part B. TRICARE for Life suspends coverage if Part B is not maintained.

14. Confusing VA coverage with MSP coverage. VA care is delivered through VA facilities under VA rules.

15. Failing to use the Medicare Secondary Payer Recovery Portal. The portal allows beneficiaries to update coverage, dispute determinations, and respond to recovery demands.

Step by Step: How to Navigate MSP Rules in Georgia

The MSP framework operates automatically through CMS Section 111 reporting and Medicare claims processing, but beneficiaries can take several steps to ensure accurate MSP determination and avoid common traps.

First, confirm employer size with HR or benefits department in writing. If you are working past age 65 with employer GHP coverage, ask HR to confirm the number of employees nationwide (not just at your worksite) and document the answer. The 20-employee threshold (working aged) or 100-employee threshold (disability) is critical for MSP-primary status and GHP SEP eligibility.

Second, complete Form CMS-L564 (Request for Employment Information) annually or whenever employment circumstances change. The form documents the employer size, the coverage type, and the period of coverage; it is critical for Part B enrollment timing and LEP avoidance.

Third, enroll in Part B at the end of active employment, not at the end of COBRA. The 8-month GHP SEP clock starts when active employment ends. Even if COBRA is available and you choose to use it, enroll in Part B during the SEP window. Failure to do so causes LEP and billing problems.

Fourth, report MSP-relevant changes to CMS through the Medicare Coordination of Benefits and Recovery Portal. Changes include: changes in employment status, changes in GHP coverage, new workers' comp or liability claims, settlements or judgments, and any other circumstances that affect MSP determination.

Fifth, work with an attorney for workers' compensation and liability settlements above the MSA review thresholds. The CMS MSA review process is complex and the consequences of improper allocation can be substantial.

Sixth, dispute improper provider billing immediately. If a provider bills you for Medicare cost-sharing as a QMB enrollee, file a complaint with DCH Medicaid Member Services (1-866-211-0950) and Medicare (1-800-MEDICARE). Federal law prohibits the improper billing.

Seventh, consult GeorgiaCares SHIP at 1-866-552-4464 for complex MSP situations. SHIP counseling is free, unbiased, and specifically trained in MSP issues affecting Georgia beneficiaries.

Frequently Asked Questions

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What is the Medicare Secondary Payer (MSP) framework?

MSP is the framework under Section 1862(b) of the Social Security Act and 42 CFR Part 411 that determines when Medicare pays primary vs. secondary to other coverage. Medicare is secondary in specific defined contexts: certain employer GHPs, workers' compensation, no-fault auto, liability insurance, and the Federal Black Lung Program. In all other contexts Medicare is primary.

What is the 20-employee rule?

Under Section 1862(b)(1)(A), an employer Group Health Plan based on current employment is primary to Medicare for beneficiaries age 65+ if the employer has 20 or more employees. Medicare is secondary. This rule supports the Working Aged GHP SEP.

What is the 100-employee rule?

Under Section 1862(b)(1)(B), an employer GHP based on current employment is primary to Medicare for SSDI beneficiaries under age 65 if the employer has 100 or more employees. Medicare is secondary.

What is the ESRD 30-month coordination period?

Under Section 1862(b)(1)(C), an employer GHP is primary to Medicare for the first 30 months of Medicare entitlement based on ESRD, regardless of employer size. After 30 months Medicare becomes primary.

Does COBRA qualify for MSP-primary status?

No. COBRA is post-employment continuation coverage, not coverage based on current employment. Medicare is primary; COBRA is secondary. This is the COBRA trap that causes many avoidable Part B LEPs.

Does retiree coverage qualify for the GHP SEP?

No. Retiree coverage is not "based on current employment" and does not qualify for the Working Aged GHP SEP under Section 1838(g). Beneficiaries with retiree coverage must enroll in Part B during the IEP at age 65.

What if my employer has fewer than 20 employees?

Medicare is primary even during your active employment. The small-employer GHP is secondary or excess. You must enroll in Part B during your IEP at age 65 to avoid LEP.

How does Medicare coordinate with workers' compensation in Georgia?

Workers' compensation is always primary to Medicare for treatment of work-related injuries under O.C.G.A. Title 34 Chapter 9 and Section 1862(b) MSP rules. Medicare pays nothing on work-related care during the active workers' comp claim. If Medicare pays conditional benefits during a dispute, CMS recovers from workers' comp proceeds.

How does Medicare coordinate with liability settlements?

Liability insurance is primary to Medicare for related medical care. If Medicare pays conditional benefits while liability litigation is pending, CMS recovers from the settlement or judgment proceeds. Larger settlements may require Medicare Set-Aside Arrangements (MSAs).

What is a Medicare Set-Aside Arrangement (MSA)?

An MSA is a trust or escrow account holding settlement funds specifically allocated for future Medicare-covered medical expenses related to an underlying injury. The beneficiary spends from the MSA for related care; Medicare does not pay until the MSA is exhausted. Common for workers' comp and liability settlements above CMS review thresholds.

How does FEHB coordinate with Medicare?

For active federal employees, FEHB is primary and Medicare is secondary. For federal retirees, coordination depends on whether the retiree enrolled in both Part B and FEHB. FEHB does not require Part B enrollment, but retirees who delay Part B may face LEP issues.

Does TRICARE for Life require Medicare Part B?

Yes. TRICARE for Life requires Part B enrollment to remain effective. Failure to enroll in Part B at age 65 causes loss of TFL coverage.

How does Medicaid coordinate with Medicare for dual-eligibles in Georgia?

Medicaid is always payer of last resort under Section 1902(a)(25). Medicare is primary for dual-eligibles. Georgia Medicaid pays Medicare cost-sharing for QMB enrollees and Medicaid-only services for full-duals. Coordination is administered through the COBA between Georgia DCH and CMS.

What is improper QMB billing?

Under Section 1902(n)(3)(B) of the SSA, providers cannot bill QMB enrollees for Medicare cost-sharing. The provider must accept the Medicare-allowed amount plus the Medicaid cost-sharing payment as payment in full. Improper QMB billing is a federal compliance issue.

How do I report improper QMB billing?

File a complaint with DCH Medicaid Member Services at 1-866-211-0950, with Medicare at 1-800-MEDICARE, or with the Office of Inspector General. GeorgiaCares SHIP can help prepare complaints.

What is Section 111 mandatory reporting?

Section 111 of MMSEA 2007 requires GHPs, liability insurers, no-fault insurers, and workers' comp entities to report information to CMS for MSP determination. Reporting is mandatory and enforced with substantial penalties for non-compliance.

What is the Medicare Secondary Payer Recovery Center?

CMS's center for handling MSP-related disputes, conditional payment recovery, and MSA review. Beneficiaries can interact through the Coordination of Benefits and Recovery Portal.

How do I update my MSP coverage information with CMS?

Use the Medicare Coordination of Benefits and Recovery Portal at MyMedicare.gov or call 1-800-MEDICARE. Update changes in employment, coverage, settlements, or other MSP-relevant circumstances promptly.

Does the MSP framework affect Medicare Advantage enrollment?

Indirectly. MA plans deliver Part A and Part B benefits; the underlying Part B enrollment is what matters for MSP. Beneficiaries with MSP-primary GHP coverage can enroll in MA but the GHP remains primary for the underlying coverage.

What is Form CMS-L564?

Form CMS-L564 (Request for Employment Information) documents employer-sponsored GHP coverage for purposes of Part B enrollment and GHP SEP eligibility. HR offices sign the form to confirm employer size, coverage type, and coverage period.

Does VA coverage operate under MSP rules?

VA care is delivered through VA facilities under VA rules and is not technically a primary or secondary payer in the MSP sense. Veterans enrolled in both VA care and Medicare can use either system; VA does not "coordinate" with Medicare in the typical payer-coordination way.

What happens if I have multiple sources of primary coverage?

The MSP framework establishes a hierarchy: workers' comp first (for work-related claims), then no-fault auto, then liability, then GHP, then Medicare, then Medicaid. Where multiple primary sources apply (e.g., a work-related injury that is also subject to liability), the most-primary source pays first.

What is the small-employer exception under MSP?

There is no formal "exception" but the practical effect of the 20-employee threshold (working aged) and 100-employee threshold (disability) is that smaller employers' GHPs are not primary under MSP. Medicare is primary even during active employment.

Can I dispute a CMS MSP determination?

Yes. Disputes can be filed through the Medicare Coordination of Benefits and Recovery Portal, the Medicare Secondary Payer Recovery Center, or in connection with a specific claim denial. Document the basis for the dispute (employer size, coverage type, settlement allocation, etc.).

Where can I get free help with MSP issues in Georgia?

GeorgiaCares SHIP at 1-866-552-4464 provides free Medicare counseling including MSP issues. Medicare Rights Center (1-800-333-4114) and Center for Medicare Advocacy (1-860-456-7790) provide national counseling. Atlanta Legal Aid (404-377-0701) and Georgia Legal Services (1-800-498-9469) provide legal representation for complex cases.

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Resources and Where to Turn Next

The Medicare Secondary Payer rules under Section 1862(b) of the Social Security Act and 42 CFR Part 411 are the framework that determines when Medicare pays primary vs. secondary to other coverage. The framework was created by TEFRA 1982 and expanded by OBRA 1986, MMA 2003, MMSEA 2007 (Section 111 mandatory reporting), 21st Century Cures 2016, and BENES 2020. The 2024 final regulations update at 89 Federal Register 17,752 made significant changes to Section 111 enforcement and conditional payment recovery procedures.

The four core MSP rules are: working aged 20-employee rule under Section 1862(b)(1)(A) (large-employer GHP based on current employment is primary, supporting the Section 1838(g) GHP SEP); disability 100-employee rule under Section 1862(b)(1)(B) (100+-employee GHP is primary for SSDI beneficiaries under 65); ESRD 30-month coordination period under Section 1862(b)(1)(C) (GHP primary regardless of employer size for first 30 months); and workers' comp, no-fault auto, and liability rule under Section 1862(b)(2) (those payers always primary to Medicare).

The most critical MSP-related issue for Georgia families is the COBRA trap: COBRA does not extend MSP-primary status for the GHP, so the 8-month Working Aged GHP SEP clock starts at the end of active employment, not at the end of COBRA. Beneficiaries should enroll in Part B at the end of active employment to avoid LEP, regardless of whether COBRA is available.

For Georgia families navigating MSP issues, the action steps are: confirm employer size with HR in writing; complete Form CMS-L564 to document GHP coverage; enroll in Part B at the end of active employment; report MSP-relevant changes through the Medicare Coordination of Benefits and Recovery Portal; consult an attorney for workers' compensation and liability settlements above MSA review thresholds; dispute improper provider billing immediately; and contact GeorgiaCares SHIP (1-866-552-4464) for free MSP counseling.

Brevy publishes deep-dive Medicaid and Medicare guides for Georgia families, including comprehensive coverage of the Part B Late Enrollment Penalty, the Medicare Savings Programs, the Buy-In framework, dual-eligible coordination, and the full ecosystem of Medicare-Medicaid interactions that depend on the MSP rules. Find personalized help understanding Medicare Secondary Payer rules in Georgia at brevy.com.

::: cta Get help with Georgia Medicare Secondary Payer issues.

Medicare 1-800-MEDICARE (1-800-633-4227) 24 hours a day, 7 days a week. Questions about MSP coordination, Part B enrollment, employer GHP issues, workers' comp coordination, liability settlement issues, and conditional payment recovery.

Social Security Administration 1-800-772-1213 (TTY 1-800-325-0778) Monday through Friday, 8:00 AM to 7:00 PM. Part B enrollment, GHP SEP applications, Form CMS-L564 processing, and Equitable Relief requests.

CMS Medicare Secondary Payer Recovery Center Access through MyMedicare.gov or call 1-800-MEDICARE Handles MSP-related disputes, conditional payment recovery, Medicare Set-Aside Arrangement (MSA) review, and Section 111 reporting issues.

Medicare Coordination of Benefits and Recovery Portal MyMedicare.gov Update MSP coverage information, dispute MSP determinations, respond to conditional payment recovery demands, and access MSP-related correspondence.

Georgia Department of Insurance 1-800-656-2298 State insurance regulator. Complaints about insurance company conduct, GHP plan administration, and other insurance-related MSP issues.

Georgia State Board of Workers' Compensation 404-656-3818 Georgia workers' compensation administration under O.C.G.A. Title 34 Chapter 9. Workers' comp claims, disputes, and MSA-related issues.

Georgia Department of Community Health (DCH) Medicaid Member Services 1-866-211-0950 Questions about Georgia Medicaid coordination with Medicare, improper QMB billing complaints, and dual-eligible coordination issues.

Division of Family and Children Services (DFCS) Customer Service 1-877-423-4746 Medicaid and SSI-related eligibility questions, including Medicare Savings Program applications and MSP coordination issues.

GeorgiaCares (SHIP) 1-866-552-4464 Free, unbiased Medicare counseling for Georgia beneficiaries including MSP analysis, GHP SEP eligibility review, COBRA trap avoidance, and complex coordination issues. The most useful starting point for any Georgia MSP issue.

AARP Georgia 1-866-295-7283 Medicare advocacy, education programs, and member benefits including MSP-related education and policy advocacy.

211 Georgia Dial 211 Statewide information and referral helpline. Free, confidential, 24/7 connections to local Medicaid help, MSP-related assistance, and social services.

Eldercare Locator 1-800-677-1116 Federal hotline operated by the Administration for Community Living. Connects Georgia families to local area agencies on aging, SHIP programs, and eldercare resources.

Medicare Rights Center 1-800-333-4114 National Medicare counseling hotline providing detailed help with MSP issues, enrollment, LEP, appeals, and complex Medicare matters.

Center for Medicare Advocacy 1-860-456-7790 National nonprofit legal advocacy organization specializing in Medicare access and enrollment issues including MSP disputes, conditional payment recovery, and MSA litigation.

Atlanta Legal Aid Senior Citizens Law Project 404-377-0701 Free legal representation for low-income Atlanta-area seniors on Medicare, Medicaid, MSP coordination, and improper billing issues.

Georgia Legal Services Program 1-800-498-9469 Statewide legal aid for low-income Georgians outside metro Atlanta on Medicare, Medicaid, MSP issues, and dual-eligible coordination. :::

Disclaimer. This guide provides general information about the Medicare Secondary Payer (MSP) framework under Section 1862(b) of the Social Security Act, 42 USC 1395y(b), and 42 CFR Part 411. It is not legal, tax, or financial advice. Federal law, regulations, CMS Internet-Only Manual provisions, and Section 111 reporting requirements change frequently, and individual circumstances vary widely. Always verify current information with Medicare (1-800-MEDICARE), the Social Security Administration (1-800-772-1213), Georgia Department of Insurance, Georgia State Board of Workers' Compensation, and GeorgiaCares SHIP (1-866-552-4464). For complex cases involving workers' compensation settlements, liability settlements, Medicare Set-Aside Arrangements, or Section 111 reporting disputes, consult an attorney experienced in MSP/MSA matters. Atlanta Legal Aid Senior Citizens Law Project (404-377-0701) and Georgia Legal Services Program (1-800-498-9469) provide free legal services for income-eligible Georgians. Brevy and its writers are not responsible for individual MSP decisions or outcomes that result from reliance on this guide. Brevy publishes at brevy.com.