Mississippi Medicare Supplement: Open Enrollment and Under 65 (2026)

Mississippi Medicare Supplement buyers under 65 who have Medicare because of a disability get a six-month open enrollment period, according to the Mississippi Insurance Department.1 The Mississippi Insurance Department (MID) regulation on Medigap bars an insurer from denying or health-pricing any Medicare Supplement policy sold in Mississippi when a person applies before or during the six months that begin the first month the person is 65 or older and enrolled in Medicare Part B.1 After that window closes, Mississippi's guaranteed issue rule gives people who lose certain coverage until 63 days after it ends to buy certain Medigap policies without being turned down or charged more for their health.1

In This Guide

• Can You Buy a Medicare Supplement Under 65 in Mississippi?
• When Is the Mississippi Medigap Open Enrollment Window?
• Will a Pre-Existing Condition Be Covered Right Away?
• When Must a Mississippi Insurer Sell You a Policy Later?
• Which Medicare Supplement Plans Can You Buy in Mississippi?
• Should You Pick Medigap or Medicare Advantage?
• What Protections Come With a Policy After You Buy?
• How Do the Mississippi Windows Compare at a Glance?
• Who Can Help You Compare Policies in Mississippi?
• Frequently Asked Questions
• Learn More

Can You Buy a Medicare Supplement Under 65 in Mississippi?

Yes: Mississippians under 65 who have Medicare because of a disability get a six-month Medicare Supplement (Medigap) open enrollment period, according to the Mississippi Insurance Department's Medicare Supplement Shopper's Guide.1 Federal law alone is thinner: Medicare.gov says people under 65 with Medicare because of a disability might not be able to buy a Medigap policy until 65, because federal law generally doesn't require insurers to sell Medigap policies to people under 65.2

MID's Mississippi Medicare Supplement Shopper's Guide sets out the under-65 disability window in four points:1

• Mississippians under 65 who qualify for Medicare due to disability have a six-month open enrollment period starting the month they qualify for Medicare.
• If Medicare makes a retroactive Part B eligibility determination, the six-month period begins on the date of the Medicare determination.
• A Mississippian under 65 who bought a Medigap policy during the disability open enrollment period gets a new six-month open enrollment period on turning 65.
• MID's guide says that second window matters because disability Medigap policies are usually priced higher.

The Centers for Medicare & Medicaid Services (CMS) backs the Mississippi under-65 right. Medicare's guide Choosing a Medigap Policy lists Mississippi among the states that, at the time of printing, require insurance companies to offer at least one kind of Medigap policy to people with Medicare under 65, and it says a person who already has Part B still gets a Medigap Open Enrollment Period on turning 65.1

Rule 10.11(D) of Mississippi's regulation adds a second under-65 right. Mississippians eligible for Medicare by reason of disability before 65 who are enrolled in a managed care plan, and whose managed care coverage ends through cancellation, nonrenewal or disenrollment, have a guaranteed right to buy certain Medicare Supplement plans from any insurer within 63 days after the termination or disenrollment date.1 Rule 10.11(D) names specific plan letters, and Rule 10.09.2 separately bars Plans C, F and F with High Deductible for people newly eligible for Medicare on or after January 1, 2020, so confirm current options with MID.1 Brevy's guide to Medigap guaranteed issue rights explains how plan letters work in these situations.

Price is the tradeoff under 65. Rule 10.11(D) lets a Mississippi insurer develop premium rates specific to the disabled population, which must be filed with and approved by the Commissioner.1

When Is the Mississippi Medigap Open Enrollment Window?

Mississippi's Medicare supplement regulation, 19 Miss. Admin. Code Part 3, Chapter 10, sets the open enrollment rule in Rule 10.11. Rule 10.11 protects an application submitted before or during the six-month period that begins with the first day of the first month a person is both 65 or older and enrolled for benefits under Medicare Part B.1

During that Mississippi open enrollment period, Rule 10.11 says an insurer may not:

• deny or condition the issuance or effectiveness of any Medicare Supplement policy available for sale in Mississippi because of the applicant's health status, claims experience, receipt of health care or medical condition;
• discriminate in the pricing of the policy for any of those same health reasons.1

Rule 10.11 also requires each Medicare Supplement policy an insurer currently offers in Mississippi to be made available to every applicant who qualifies for open enrollment.1

The Mississippi window tracks the federal floor. Section 1882 of the Social Security Act bars a Medigap insurer from denying, conditioning or health-pricing a policy for an application submitted before or during the six-month period beginning with the first month a person is 65 or older and enrolled in Part B, and Medicare.gov calls the Medigap Open Enrollment Period a one-time window that doesn't repeat every year.2 Outside that federal window, Medicare.gov says an insurer may use medical underwriting to deny a Medigap policy, may charge more, and may offer fewer options, although state law can add rights.2 Brevy's national guide to the Medigap open enrollment period covers the federal timing in more detail.

Will a Pre-Existing Condition Be Covered Right Away?

Being sold a Mississippi Medicare Supplement policy and having every condition covered on day one are separate questions. Rule 10.11 of Mississippi's Medigap regulation handles pre-existing conditions for open enrollment applicants in three branches, based on prior creditable coverage:1

1. Six months or more of continuous creditable coverage: The insurer shall not exclude benefits based on a preexisting condition.
2. Less than six months of continuous creditable coverage: The insurer shall reduce any preexisting condition exclusion period by the total time of that prior creditable coverage.
3. Other cases: Apart from those credits and the exceptions in Rules 10.12 and 10.23, a Mississippi Medicare Supplement policy may exclude benefits during its first six months for a condition treated or diagnosed during the six months before coverage became effective.

Medicare's guide Choosing a Medigap Policy, published by CMS, states that prior creditable coverage counts only if the break in coverage was no more than 63 days, so a Mississippian moving to Medicare from job-based or other health coverage should keep the dates of that coverage.1 Brevy's guide to Medigap and pre-existing conditions explains the look-back period.

When Must a Mississippi Insurer Sell You a Policy Later?

Rule 10.12 of Mississippi's Medigap regulation, titled Guaranteed Issue for Eligible Persons, covers people who apply outside open enrollment after losing certain coverage. For an eligible person, Rule 10.12 says a Mississippi insurer shall not deny or condition a Medicare Supplement policy described in the rule, shall not price it on health, and shall not impose a preexisting condition exclusion.1

The eligible persons Rule 10.12 describes include people in these situations:1

1. Employer coverage ends: An employee welfare benefit plan that supplements Medicare terminates or stops providing all of those supplemental benefits.
2. Medicare Advantage plan ends or fails you: The plan's certification is terminated, the organization stops offering the plan where you live, you are no longer eligible because of a move or other change the Secretary specifies, or you show the organization substantially violated a material contract provision or materially misrepresented the plan in marketing. Similar circumstances apply to a person 65 or older enrolled with a Program of All-Inclusive Care for the Elderly (PACE) provider.
3. Medigap policy ends: The insurer becomes insolvent or bankrupt, the coverage ends involuntarily, or the insurer substantially violated a material policy provision or materially misrepresented the policy in marketing.
4. First-time Medicare Advantage trial: You dropped a Medicare Supplement policy to enroll for the first time in a Medicare Advantage plan (or certain other plans, a PACE provider, or a Medicare SELECT policy) and end that enrollment within the first 12 months.
5. Medicare Advantage or PACE at 65: You enrolled in a Medicare Advantage plan or with a PACE provider on first becoming eligible for Part A at 65 and disenroll within 12 months of the enrollment's effective date.

If your situation is not one of those listed here, Medicare's Choosing a Medigap Policy guide says to call your State Health Insurance Assistance Program (SHIP) to make sure you qualify for a guaranteed issue right.1 Rule 10.12 limits a guaranteed issue right to certain Medicare Supplement policies, and the plan letters it names differ by situation; Brevy's guide to Medigap guaranteed issue rights covers which policies the federal situations reach.

How long does a Mississippi guaranteed issue period last?

Mississippi's guaranteed issue periods end 63 days after the applicable coverage ends or the disenrollment takes effect, and for a voluntary disenrollment the period begins 60 days before the disenrollment's effective date.1 MID's Shopper's Guide says a Mississippian 65 or older has a guaranteed issue right within 63 days of losing or ending certain kinds of health coverage, and that during it companies must sell a Medigap policy at the best available rate regardless of health status.1

Rule 10.12 also requires an eligible person to submit evidence of the date of termination, disenrollment or Medicare Part D enrollment with the Medicare Supplement application.1 The FAQ below lists the papers CMS suggests keeping as that proof.

Switching Medigap policies without a guaranteed issue right is harder. Medicare.gov says that, under federal rights, in most cases you won't be able to switch Medigap policies outside your six-month Medigap Open Enrollment Period unless you have a guaranteed issue right, and that switching outside it may mean paying more and answering medical questions.3

Which Medicare Supplement Plans Can You Buy in Mississippi?

Rule 10.09.1 of Mississippi's regulation requires every Medicare Supplement insurer to make available a policy form containing only the basic (core) benefits, and Medicare's Choosing a Medigap Policy guide says every insurer selling Medigap policies must offer at least Plan A.1 A Mississippi insurer that offers any additional benefits, or standardized Plans K or L, must also offer Plan C or Plan F under Rule 10.09.1.1

The Plan C and Plan F requirement changed in 2020. Rule 10.09.2 of Mississippi's regulation says that for people newly eligible for Medicare on or after January 1, 2020, Plan C is redesignated as Plan D and Plan F as Plan G, neither covering the Part B deductible, and Plans C, F and F with High Deductible may not be offered to them.1 Medicare's guide adds that someone who was eligible for Medicare before January 1, 2020 but hasn't yet enrolled may still be able to buy Plan C or Plan F.1

Medicare's Choosing a Medigap Policy guide charts the standardized Medigap plans as Plans A, B, C, D, F, G, K, L, M and N, and says Plans E, H, I and J are no longer sold, though a person who already has one can generally keep it.1 Brevy's guides to how the lettered Medigap plans work and to Plan G versus Plan N compare the letters benefit by benefit.

Should You Pick Medigap or Medicare Advantage?

A Medigap policy works only alongside Original Medicare. The CMS booklet Understanding Medicare Advantage Plans states that you can't use a Medigap policy to pay Medicare Advantage Plan copayments, coinsurance, deductibles or premiums.4 The same CMS booklet sets two more rules:

• If you are in a Medicare Advantage Plan, it's illegal for anyone to sell you a Medigap policy unless you're switching back to Original Medicare, and the booklet says to report an attempted sale to your State Insurance Department.
• In most cases, if you drop a Medigap policy to join a Medicare Advantage Plan, you may not be able to get the same policy back.4

First-time Medicare Advantage members have a way back. The CMS booklet says a person who joins a Medicare Advantage Plan for the first time and isn't happy with it has a "trial right" under federal law to buy a Medigap policy and a separate Medicare drug plan if returning to Original Medicare within 12 months of joining.4 Mississippi's Rule 10.12 covers the same ground in the fourth and fifth situations listed above, for people who leave a first-time Medicare Advantage or PACE enrollment within 12 months.1 Brevy's guide to Medicare Advantage trial rights walks through the federal timing.

What Protections Come With a Policy After You Buy?

Mississippi's Medicare supplement regulation sets two protections that apply once a policy is issued, and MID's Shopper's Guide explains a third point to check:1

• Guaranteed renewable: Every Mississippi Medicare Supplement policy must be guaranteed renewable, and the insurer may not cancel or non-renew it for any reason other than nonpayment of premium or material misrepresentation.
• 30-day return: A Mississippi Medicare Supplement policyholder may return the policy within 30 days of its delivery and have the premium refunded if not satisfied for any reason.
• Rating method: Under an issue-age schedule, the premium is based on your age when the policy was first issued and cannot rise simply because you get older; under an attained-age schedule, the premium is based on your age on each premium due date.

Federal law sets the same floors. Section 1882(c)(4) of the Social Security Act lets a Medigap policy be returned for a full refund of premiums during a period of at least 30 days after it is issued, and Medicare's Choosing a Medigap Policy guide says any new Medigap policy issued since 1992 is guaranteed renewable even if you have health problems.3,1

The rating method decides what a Mississippi policy costs years from now, not just in the first year, so ask each insurer which schedule a quote uses. Brevy's guide to how Medigap premiums are priced compares the rating methods side by side.

How Do the Mississippi Windows Compare at a Glance?

The Mississippi table summarizes Rules 10.09 through 10.12 of 19 Miss. Admin. Code Part 3, Chapter 10 and MID's Shopper's Guide; the sections above give the exact wording.1

Who Can Help You Compare Policies in Mississippi?

• MID counseling: MID's Medicare page says Mississippians can get Medicare and health insurance counseling from the Mississippi Insurance Department at (601) 359-3569 or (800) 562-2957.1
• MID Consumer Services Division: MID's Shopper's Guide says its Consumer Services Division can be reached at 601-359-3569 in the Jackson area or statewide toll-free at 1-800-562-2957, and that counseling on buying Medicare Supplement insurance and on Medicaid is available without charge.1
• MDHS aging counseling: MID's Medicare page lists the Mississippi Department of Human Services (MDHS) Division of Aging and Adult Services as a Medicare counseling contact at (601) 359-4956 or (888) 240-7539.1
• SHIP locator: Medicare's Choosing a Medigap Policy guide says to visit shiphelp.org for the number of your local State Health Insurance Assistance Program (SHIP), and to call your SHIP to confirm you qualify for a guaranteed issue right.1
• 1-800-MEDICARE: For Original Medicare questions, 1-800-MEDICARE (1-800-633-4227) is the official line run by CMS, TTY users call 1-877-486-2048, and Medicare.gov says callers can reach a real person 24 hours a day, 7 days a week, except some federal holidays.5

Brevy's Mississippi Medicare hub covers the rest of Medicare in the state, and its guide to Mississippi Medicare Savings Programs covers help with Medicare costs.

Learn More

Find personalized help timing your Mississippi Medicare Supplement window and checking an under-65 or guaranteed issue right at brevy.com.

The information on Brevy.com is for educational purposes only and is not a substitute for professional legal, financial, or medical advice. Rules vary by state and program and change frequently. Always verify with the relevant agency or a qualified professional. Brevy is not a law firm, financial advisor, or healthcare provider.