Georgia Medicare Shared Savings Program MSSP Guide 2026

The Medicare Shared Savings Program (MSSP) is the largest and most consequential value-based care program in American health care. Established by Section 3022 of the Patient Protection and Affordable Care Act of 2010 and codified at Section 1899 of the Social Security Act, MSSP launched in 2012. Unlike CMS Innovation Center models such as ACO REACH (which operate under time-limited testing authority), MSSP is a permanent Medicare program.

MSSP has hundreds of participating Accountable Care Organizations (ACOs) serving millions of traditional Medicare Fee-for-Service beneficiaries nationally and has generated substantial net Medicare Trust Fund savings since inception.

For Georgia specifically, MSSP penetration is substantial. Major Georgia integrated systems participate, including Wellstar Health System (northern Georgia), Emory Healthcare Network (metropolitan Atlanta), Piedmont Healthcare (Atlanta and statewide), and other regional systems. Independent primary care networks including Aledade (which partners with independent primary care practices nationally) and Privia Medical Group (Privia Health Georgia) operate Georgia-focused MSSP ACOs. Many Georgia Medicare beneficiaries are aligned to MSSP ACOs through their primary care providers.

MSSP underwent a fundamental restructuring through the Pathways to Success Final Rule published in late 2018. Pathways to Success replaced the original three-track structure (Tracks 1, 2, 3) with the current BASIC Track (with five risk levels: A, B, C, D, E) and ENHANCED Track. It accelerated ACOs' transition into two-sided risk and recalibrated benchmarking methodology.

In late 2022, CMS issued the CY 2023 Medicare Physician Fee Schedule Final Rule with major MSSP provisions: it reintroduced Advance Investment Payments (AIPs) (capital advances for new low-revenue ACOs serving underserved populations); added health equity benchmark adjustments parallel to those in ACO REACH; modified the BASIC track glide path to give new ACOs more time before mandatory risk-bearing; and made other technical refinements.

For Georgia Medicare Fee-for-Service beneficiaries, MSSP alignment is administrative. Your Medicare benefits do not change, your provider choice is unchanged, your cost-sharing is identical, and you may opt out at any time. What does change behind the scenes: your primary care provider becomes part of an ACO accountable for total cost of care and quality, and the ACO may invest in care coordination, chronic disease management, transitional care management, and preventive outreach.

This guide walks Georgia Medicare beneficiaries and providers through the full MSSP framework: the statutory authority, the BASIC and ENHANCED track structure, the Pathways to Success redesign, the 2022 reforms reintroducing AIPs, the benchmarking and quality reporting methodology, the connection to the MACRA Quality Payment Program, the beneficiary alignment and protections, the Georgia MSSP participants, and how MSSP relates to the ACO REACH Innovation Center model.

Statutory Authority and Program History

Section 1899 of the Social Security Act — MSSP

Section 1899 was added to the Social Security Act by Section 3022 of the Patient Protection and Affordable Care Act of 2010. It established MSSP as a permanent Medicare program designed to:

• Test whether groups of providers organized as ACOs can deliver better-coordinated care to traditional Medicare FFS beneficiaries
• Share savings with ACOs that meet quality benchmarks
• Reduce Medicare Trust Fund spending growth

Unlike CMS Innovation Center models authorized under Section 1115A (which operate as time-limited tests), MSSP under Section 1899 is permanent, though CMS may modify the program through notice-and-comment rulemaking.

Implementation timeline

2012: MSSP operational launch. Original tracks:

• Track 1: upside-only shared savings (no downside risk)
• Track 2: two-sided risk
• Track 3: highest risk and reward

2015-2018: program growth and refinement. Most ACOs participated in upside-only Track 1.

Pathways to Success Final Rule (2018): comprehensive redesign. Replaced Tracks 1/2/3 with:

• BASIC Track: glide path through Levels A (upside-only) → B (upside-only) → C (two-sided) → D (two-sided) → E (two-sided)
• ENHANCED Track: highest risk/reward, successor to Track 3

The reform shortened the upside-only window. Under the original program, ACOs could remain in Track 1 (upside-only) indefinitely; Pathways to Success limited upside-only participation to 2-3 years for most ACOs, with mandatory transition to two-sided risk thereafter.

CY 2023 PFS Final Rule (late 2022): Biden-era CMS reforms responding to concerns that Pathways to Success had been too aggressive in pushing risk:

• Reintroduced Advance Investment Payments (AIPs) (capital advances for new low-revenue ACOs serving underserved populations, echoing the earlier ACO Investment Model)
• Modified the BASIC track glide path to give new low-revenue ACOs additional years before mandatory two-sided risk
• Added health equity benchmark adjustments parallel to ACO REACH
• Other technical refinements

CY 2024 and subsequent PFS Final Rules: continued refinements including prepaid shared savings options, quality measure adjustments, and benchmarking methodology updates.

Connection to MACRA 2015 Quality Payment Program

The Medicare Access and CHIP Reauthorization Act of 2015 (MACRA) established the Quality Payment Program (QPP) for Part B physician payments, replacing the Sustainable Growth Rate (SGR). QPP has two tracks:

• Merit-Based Incentive Payment System (MIPS) (performance-based payment adjustment)
• Advanced Alternative Payment Model (Advanced APM) track (participation in qualifying APMs exempts clinicians from MIPS and qualifies them for incentive payments)

Two-sided MSSP tracks (BASIC Levels C, D, E and ENHANCED) qualify as Advanced APMs under MACRA. Clinicians participating sufficiently in Advanced APMs receive APM Incentive Payments and the qualifying APM conversion factor differential.

This MACRA Advanced APM status is a major financial driver of MSSP participation. For high-volume physician groups, Advanced APM status materially affects Medicare Part B payment.

Program Structure

BASIC Track

The BASIC Track has five risk levels (Levels A through E), structured as a glide path for ACOs to transition from upside-only to two-sided risk:

Level A (upside-only)

• Shared savings rate applies; no downside risk
• Typical for new ACOs

Level B (upside-only)

• Same as Level A
• Second year of upside-only typically

Level C (two-sided risk)

• Shared savings rate applies
• Shared losses apply; recoupment limit applies

Level D (two-sided risk)

• Same structure as Level C with higher loss recoupment limit

Level E (two-sided risk)

• Same structure with highest loss recoupment limit

ACOs progress through levels over time. Under the original Pathways to Success rules, the glide path was 2-3 years upside-only before mandatory two-sided risk. The CY 2023 PFS Final Rule extended this for new low-revenue ACOs.

ENHANCED Track

• Highest maximum shared savings rate
• Shared losses apply; highest loss recoupment limit
• Highest risk and highest reward
• Generally for experienced ACOs with strong infrastructure
• Qualifies as Advanced APM under MACRA

Beneficiary Population

ACOs must meet minimum aligned beneficiary population requirements as determined by CMS program rules. High Needs Population provisions may modify thresholds.

ACO Types

MSSP recognizes various ACO compositions:

• Hospital-led ACOs (integrated systems)
• Physician-led ACOs (medical groups)
• Mixed ACOs
• Federally Qualified Health Center (FQHC) and Rural Health Clinic (RHC) participation

Advance Investment Payments (AIPs)

The CY 2023 PFS Final Rule reintroduced AIPs for new low-revenue ACOs serving underserved populations:

• One-time payment at start of agreement
• Quarterly payments per aligned beneficiary for a defined period
• ACO uses funds to build infrastructure (care management, health IT, community health workers)
• Repayment from shared savings over time

AIPs respond to the persistent finding that low-revenue ACOs (physician-led, primary care-focused) outperform high-revenue ACOs (hospital-led) on Medicare savings, but lack capital to start.

Benchmarking Methodology

MSSP benchmarking uses a blended approach:

• Historical baseline: ACO's aligned population's prior Medicare FFS spending
• Regional adjustment: comparison to regional spending
• National trend factor: applied to project benchmark forward
• Risk adjustment: CMS-HCC adjustment for beneficiary clinical complexity
• Coding Intensity Factor (CIF): limits inappropriate risk score inflation
• Health Equity Benchmark Adjustment (added 2023): upward adjustment for ACOs serving more socioeconomically disadvantaged populations (similar to ACO REACH)

Benchmarks are set at the start of the agreement period and trended forward through the 5-year agreement. Post-rebasing methodology has evolved through successive rules.

Quality Reporting: Alternative Payment Model Performance Pathway (APP)

MSSP quality reporting transitioned from the Web Interface (legacy) to the Alternative Payment Model Performance Pathway (APP) in recent performance years. APP uses a streamlined measure set:

• CAHPS for ACOs (patient experience)
• Risk-standardized all-cause readmission
• Depression screening and follow-up
• Diabetes HbA1c control
• Hypertension blood pressure control
• Statin therapy for cardiovascular disease prevention
• Other measures (set evolves annually)

ACO quality performance affects:

• Shared savings/losses calculations (higher quality = higher shared savings rate)
• MACRA Advanced APM threshold determinations
• Public reporting (Medicare.gov ACO performance data)

Beneficiary Alignment

Claims-Based Alignment

The primary method. CMS attributes a beneficiary to an MSSP ACO based on plurality of primary care utilization with participating providers, using historical claims look-back.

Voluntary Alignment

Beneficiaries may actively elect MSSP alignment by signing an alignment form provided by their participating PCP.

Alignment Notification

Aligned beneficiaries receive a notification letter from CMS explaining alignment and opt-out rights.

Opt-Out Rights

Beneficiaries may opt out of MSSP alignment at any time. Opting out does not change Medicare benefits, provider choice, or cost-sharing.

What Doesn't Change for Aligned Beneficiaries

• All traditional Medicare Parts A and B benefits remain
• Provider choice (beneficiary may see any Medicare-enrolled provider)
• Cost-sharing is identical
• MSN and Medicare claims processing are unchanged
• Beneficiary is not "enrolled" in a new plan

Care Coordination Services Available to Aligned Beneficiaries

MSSP ACOs may offer or facilitate:

• Chronic Care Management (CCM) (care management for beneficiaries with two or more chronic conditions)
• Transitional Care Management (TCM) (post-hospitalization care management)
• Annual Wellness Visits (AWVs)
• Behavioral Health Integration
• Advance Care Planning
• Home-Based Primary Care (for High Needs populations)
• Community Health Worker outreach
• Care management for socially vulnerable beneficiaries

These services are typically beneficiary-friendly: care manager outreach, post-hospital check-ins, medication review, transportation assistance.

Georgia MSSP Participants

Wellstar Health System

Wellstar (Georgia's largest integrated delivery system, with hospitals across northern Georgia) participates in MSSP through Wellstar Health Network ACO. Wellstar's MSSP participation covers a large aligned beneficiary population across Cobb, Cherokee, Douglas, Paulding, Bartow, and surrounding counties.

Emory Healthcare Network

Emory Healthcare (Atlanta-based academic medical center system) participates through Emory Healthcare Network MSSP ACO. Emory's MSSP covers metropolitan Atlanta primarily.

Piedmont Healthcare

Piedmont Healthcare (Atlanta-based with hospitals statewide) participates through Piedmont MSSP ACO covering metropolitan Atlanta and other Piedmont service areas.

Aledade-affiliated ACOs

Aledade partners with independent primary care practices nationally. Multiple Aledade ACOs include Georgia primary care practices.

Privia Medical Group

Privia Health Georgia (large primary care medical group) operates a Georgia-focused MSSP ACO.

Other Georgia MSSP Participants

Other regional integrated systems, FQHCs, and independent physician groups participate. Performance Year rosters change; current participation can be confirmed via Medicare.gov and the CMS MSSP public participant lists.

MSSP vs. ACO REACH Comparison

Many primary care practices and integrated systems must choose between MSSP and ACO REACH (cannot participate in both simultaneously for the same beneficiaries). Practices' choices depend on risk appetite, capitation infrastructure, and capital position.

Worked Examples

Example 1: Fulton 70, Emory PCP Aligned to Emory MSSP ACO

A 70-year-old Atlanta beneficiary in Fulton County has her primary care with an Emory Healthcare Network primary care physician. Her PCP participates in Emory Healthcare Network MSSP ACO. She receives an alignment notification letter from CMS explaining the MSSP alignment. Her traditional Medicare benefits, provider choice, and cost-sharing are unchanged. She continues to see her PCP and any specialists she chooses. Behind the scenes, the ACO's care coordination program identifies her as eligible for annual wellness visit outreach and chronic disease management for her hypertension and Type 2 diabetes.

Example 2: DeKalb 75, Dual Eligible MSSP Alignment to Piedmont

A 75-year-old DeKalb County beneficiary is dually eligible for Medicare and Georgia Medicaid (full-benefit dual eligible) and has her primary care through a Piedmont Healthcare practice. The Piedmont MSSP ACO receives a Health Equity Benchmark Adjustment (introduced by the CY 2023 PFS Final Rule) recognizing her dual eligible status and the socioeconomic profile of her neighborhood. The ACO uses additional benchmark headroom to fund community health worker outreach, medication therapy management, and transportation assistance for her medical appointments.

Example 3: Cobb 68, Voluntary Alignment via Wellstar

A 68-year-old Cobb County beneficiary, newly turning 65 last year, selects a Wellstar primary care physician. At her first visit, the practice's intake staff explains MSSP and offers her a voluntary alignment form. She signs. Her MSSP alignment is established immediately, and she receives her alignment notification letter from CMS shortly thereafter. Her PCP can now bill her CCM and annual wellness visits, and the ACO's analytics team includes her in care coordination cohorts.

Example 4: Worth County 72, Rural Aledade ACO

A 72-year-old Worth County (rural south Georgia) beneficiary sees a local independent primary care physician. The physician is a member of an Aledade-affiliated MSSP ACO. Aledade provides the physician with care management infrastructure, claims data and analytics, and population health support that would otherwise be infeasible for a small rural practice. The beneficiary receives an alignment notification letter from CMS. The Aledade-supported care team identifies the beneficiary for chronic kidney disease management and proactive specialist referrals.

Example 5: Bibb 80, Care Coordination Outreach

An 80-year-old Bibb County beneficiary has multiple chronic conditions and was recently hospitalized for COPD exacerbation. Her PCP participates in a Piedmont MSSP ACO. Within 48 hours of hospital discharge, an ACO care manager calls her to schedule a Transitional Care Management visit, review her discharge medications, and arrange follow-up. The TCM visit identifies a medication reconciliation error (duplicate prescriptions from the hospital and PCP) that is corrected. The ACO bills TCM under CPT 99495 or 99496 depending on complexity.

Example 6: Hall 67, ENHANCED Track ACO

A 67-year-old Hall County beneficiary's PCP joined an ENHANCED Track MSSP ACO affiliated with a large integrated system. ENHANCED Track is the highest-risk MSSP track with the highest shared savings and losses rates. The ACO has invested heavily in care coordination, health IT, and population health infrastructure. The beneficiary receives more aggressive care management outreach than typical, including annual wellness visit nudges, chronic disease management, and post-acute care navigation. Her Medicare benefits remain unchanged.

Best Practices

1. Read the alignment notification letter carefully (it explains MSSP alignment and opt-out rights).
2. Understand that MSSP is administrative attribution, not enrollment in a new plan (traditional Medicare benefits do not change).
3. Ask your PCP whether they participate in MSSP or ACO REACH (most Georgia integrated systems and large primary care networks participate in one or the other).
4. Use 1-800-MEDICARE for alignment questions or opt-out.
5. Continue to review your Medicare Summary Notice quarterly (MSN processing is unchanged).
6. Use GeorgiaCares SHIP at 1-866-552-4464 for free Medicare counseling on MSSP and other questions.
7. Take advantage of care coordination services (annual wellness visits, chronic care management, transitional care management are beneficiary-friendly).
8. For providers: understand the Pathways to Success glide path (most new ACOs have 2-3 years upside-only before mandatory two-sided risk).
9. For providers: consider Advance Investment Payments (AIPs) if your ACO is new and low-revenue serving underserved populations.
10. For providers: align quality reporting with the Alternative Payment Model Performance Pathway (APP) (the streamlined measure set).
11. For providers: leverage MACRA Advanced APM status in two-sided tracks (material Part B payment implications).
12. For providers: build community health worker capability (increasingly important post-2023 equity adjustments).
13. For ACO leadership: monitor benchmark methodology rule changes (annual PFS rules modify MSSP mechanics).
14. For all stakeholders: distinguish MSSP from ACO REACH (different rules, different risk structures, different quality reporting).

Common Issues

1. Beneficiary confusion that MSSP is Medicare Advantage (it is not; traditional Medicare benefits and provider choice remain).
2. Alignment notification letter ignored or misread (beneficiaries should keep the letter for reference).
3. Voluntary alignment confusion (practices must explain clearly; no coercion permitted).
4. Care manager outreach mistaken for sales calls (SMP and 1-800-MEDICARE can help verify authenticity).
5. Provider transition to two-sided risk apprehension (Pathways to Success accelerated risk transition; 2023 rule provided some relief for new low-revenue ACOs).
6. Benchmarking methodology disputes (annual PFS rules modify benchmarks; ACOs must track methodology changes).
7. Quality reporting transition challenges (Web Interface to APP transition required infrastructure investment).
8. Coding intensity disputes (ACOs may aggressively code HCC diagnoses; CIF limits inappropriate inflation).
9. MSSP-MA enrollment overlap (MA enrollees are not MSSP-aligned; MA-to-FFS switchers' alignment may shift).
10. Specialty care navigation (MSSP does not restrict specialty care; beneficiaries may see any Medicare provider).
11. Care continuity when ACO participation changes (if PCP leaves an ACO, alignment shifts).
12. MACRA Advanced APM threshold complexity (clinicians must meet QP threshold to receive APM Incentive Payments).
13. Disparities in ACO performance by ACO type (physician-led/low-revenue ACOs outperform hospital-led/high-revenue ACOs on savings, which has policy implications).
14. ACO vs. ACO REACH choice for primary care practices (practices must choose; the choice depends on risk appetite, capitation infrastructure, and capital).

Call to Action: Contacts and Resources

If you have questions about MSSP alignment, want to opt out, or need help understanding your Medicare benefits:

1. Medicare: 1-800-MEDICARE (1-800-633-4227) (Medicare.gov)
2. GeorgiaCares SHIP: 1-866-552-4464 (free Medicare counseling)
3. CMS MSSP: cms.gov/medicare-shared-savings-program
4. Medicare Rights Center: 1-800-333-4114
5. Palmetto GBA Part A/B MAC: 1-866-238-9650
6. Wellstar Health System: 1-770-956-STAR (7827)
7. Emory Healthcare: 404-778-7777
8. Piedmont Healthcare: (system main line)
9. Aledade: aledade.com (provider-facing)
10. Privia Medical Group Georgia: priviahealth.com
11. Atlanta Legal Aid: 404-377-0701
12. Georgia Legal Services: 1-800-498-9469
13. Eldercare Locator: 1-800-677-1116
14. 211 Georgia: 211
15. Acentra Health QIO: 1-844-455-8708
16. SSA: 1-800-772-1213
17. BCRC (Medicare Secondary Payer): 1-855-798-2627

For every Georgia Medicare beneficiary whose PCP participates in MSSP, the most important things to understand are: your Medicare benefits do not change, you can see any Medicare provider, your cost-sharing is the same, and you can opt out at any time. MSSP is the permanent foundation of Medicare's accountable care program, an experiment that has matured into the dominant value-based care program in the United States.

The Medicare Shared Savings Program represents the most successful and durable value-based care reform of the post-ACA era. MSSP is the operational backbone of accountable care in traditional Medicare. Whether you're a beneficiary aligned to Wellstar, Emory, Piedmont, an Aledade-affiliated ACO, or a Privia Medical Group practice, MSSP shapes how your primary care provider thinks about coordinating your care, managing your chronic conditions, and preventing avoidable hospitalizations, all without changing your Medicare benefits.

Find personalized help understanding your Medicare options at brevy.com.