Medicare Special Enrollment Periods and Qualifying Events

Medicare Special Enrollment Periods let you sign up for Medicare or change your coverage outside the usual enrollment windows when a specific life event qualifies you. Each event has its own deadline, and each has its own rules about what you can change. The common ones are losing job-based health insurance, moving, being released from incarceration, losing Medicaid or Extra Help, living through a declared disaster, and being misled by a government representative. Miss the window and you generally wait for the General Enrollment Period, often with a permanent premium penalty attached.¹

Losing Job-Based Health Coverage

This is the Special Enrollment Period most people use. If you put off Part B because you or your spouse had insurance through a current employer, you get eight months to sign up once that coverage ends. The clock starts the month the employment ends or the month the group health plan ends, whichever comes first.²

Here is the trap. COBRA does not count as coverage based on current employment. Neither does retiree health coverage, VA coverage, or an individual plan bought through the Health Insurance Marketplace. If you retire at 66, elect COBRA, and wait 18 months for COBRA to run out before enrolling in Part B, your eight-month SEP is long gone. You would then have to wait for the General Enrollment Period and pay a lifetime penalty.³

When Part B actually starts depends on when in the eight months you enroll. Sign up while you still have the employer plan or during the first full month after it ends, and you can pick a start date as early as the first day of the month you enroll or the first of any of the next three months. Enroll during any of the remaining seven months and coverage begins the first day of the month after you enroll.²

Moving or Returning From Abroad

A move often opens an SEP for Medicare Advantage and Part D. If you move outside your current plan’s service area, you can switch to a plan in your new location. Even if you stay in the same service area, gaining access to new plan options where you now live qualifies you to switch.⁴

You have two full months after the month you move. Tell your plan before you move and the window opens a month earlier, so it starts the month before the move and runs through two months after. Miss it and you wait for the Annual Open Enrollment Period, which can leave you stuck in a plan with no local providers.⁴

Moving back to the United States after living abroad also opens an SEP. If you were not enrolled in Part B or Part D while overseas, you can sign up when you return without waiting for the General Enrollment Period.

Release From Jail or Prison

People released from incarceration qualify for an SEP because Medicare benefits generally cannot be used while someone is in custody. The window begins the day of release and lasts 12 full months, letting you enroll in Parts A and B without a late enrollment penalty.⁵ The 12-month period applies to anyone released on or after January 1, 2023.⁶ Before 2023 the window was much shorter, and many people missed it.

Losing Medicaid, Extra Help, or Dual-Eligible Status

If you lose Medicaid eligibility or lose Extra Help (the Low-Income Subsidy for Part D), you have three full months to adjust your Medicare Advantage or Part D coverage. The three months run from either the date you lose eligibility or the date you are notified, whichever is later.⁴

People who currently have both Medicare and Medicaid, or who get Extra Help, have a broader right. They can switch Part D plans or drop a Medicare Advantage plan with drug coverage once per calendar month, with changes taking effect the first of the next month. Full Medicaid recipients can also join or switch to an integrated Dual Eligible Special Needs Plan (D-SNP) once per calendar month.⁴

Special Needs Plan Situations

Different Special Needs Plans have different enrollment rules. If you have a severe or disabling condition and a Chronic Condition SNP in your area serves people with that condition, you can join at any time. Once you enroll, that particular SEP closes.⁴

If you live in a nursing home or similar institution, you can join an Institutional SNP at any time while you are a resident and for two full months after you move out. Dual Eligible SNPs follow the monthly switching rule described above.

Lose the qualifying status that got you into an SNP and you get an SEP to switch to a regular Medicare drug plan or another Medicare Advantage plan. That window starts the month you lose status and ends either when you join another plan or three months after you are involuntarily disenrolled, whichever comes first.⁴

A Five-Star Plan Comes to Your Area

Medicare rates plans on a one-to-five-star scale each year. When a Medicare Advantage plan, Part D plan, or Medicare Cost Plan in your area earns five stars, you get a one-time SEP to switch into that plan. The window runs from December 8 through November 30 of the following year, and you can only use it once during that cycle.⁴ This is one of the few SEPs that has nothing to do with a life disruption. CMS publishes ratings each fall, so checking whether a five-star plan reached your area is worth the few minutes.

Disasters and Government Errors

When a federal, state, or local government declares an emergency or disaster, people in the affected area who missed an enrollment deadline because of it qualify for an SEP. The window lasts for the duration of the emergency plus two additional months after the declared end date. If your documents were destroyed or are inaccessible, you can attest to living in the affected area rather than producing proof.⁷ You must have already been eligible for some other enrollment period at the time of the disaster and been prevented from acting on it. Qualifying events have included FEMA-declared hurricanes, wildfires, and flooding, plus the COVID-19 public health emergency.⁸

A separate SEP exists if you joined the wrong plan, missed a deadline, or made a bad choice because a federal employee or someone authorized to act on the government’s behalf gave you incorrect information. The window lasts two full months after the month Medicare sends a notice acknowledging the error.⁴ Getting that notice is the hard part. You generally have to contact Medicare or Social Security, explain what happened, and provide any written correspondence documenting the bad advice. Without evidence, these requests rarely succeed.

What Enrolling Through an SEP Saves You

The penalties an SEP protects you from are permanent and they compound. For every full 12-month period you could have had Part B but did not sign up, your monthly premium rises by 10%. With the 2026 standard Part B premium at $202.90, waiting two years past initial eligibility adds $40.58 per month for as long as you have Part B. That surcharge never comes off.¹

The Part D penalty is calculated differently. You are charged 1% of the national base beneficiary premium for each full month you went without creditable drug coverage after becoming eligible. In 2026, the national base beneficiary premium is $38.99, so each uncovered month adds about $0.39 to your monthly premium. Twenty-four uncovered months means roughly $9.36 extra per month, permanently.⁹ Enrolling within a valid SEP, or keeping creditable drug coverage in the meantime, stops the penalty from building up.¹

Medigap Follows Different Rules

Some events that trigger a Medicare SEP also give you guaranteed issue rights for a Medigap policy, meaning an insurer cannot deny you coverage or charge more because of your health. Losing employer coverage or losing a Medicare Advantage plan that leaves your service area are the typical examples. The strongest Medigap protection, though, is the one-time six-month Medigap Open Enrollment Period that begins the first month you have Part B and are 65 or older. During those six months, any company selling Medigap in your area must sell you any policy it offers at the standard price.¹⁰

Federal law does not require insurers to sell Medigap policies to people under 65 who qualify for Medicare through disability, though some states do. State rules on additional Medigap protections vary, so a call to your State Insurance Department is worth making.¹⁰

Enrolling and What to Send

For the most common scenario, enrolling in Part B after losing job-based coverage, you need two forms. Form CMS-40B is the actual Part B application. Form CMS-L564 (Request for Employment Information) is where your employer verifies your coverage dates in Section B after you fill out Section A. Both are on the CMS website, and both go in together. An unsigned L564 is one of the most common reasons applications stall.¹¹

For a move-related SEP, keep proof of your new address, such as a lease, mortgage statement, or utility bill. For a government-error claim, hold onto any written correspondence that documents the mistake.

You can submit Part B forms online through Social Security, or fax or mail them to your local Social Security office.¹² The online portal is generally fastest. If you mail your paperwork, get a tracking receipt in case you later need to prove you submitted within the SEP window. Processing typically takes four to eight weeks. For Medicare Advantage and Part D changes, contact the new plan directly or enroll through Medicare.gov; coverage usually begins the first day of the month after the plan receives your request.¹³

1
Medicare.gov. Avoid Late Enrollment Penalties
2
Social Security Administration. How to Apply for Medicare Part B During Your Special Enrollment Period
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Medicare.gov. Working Past 65
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Medicare.gov. Special Enrollment Periods
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Medicare.gov. Signing Up for Medicare After Jail or Incarceration
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Social Security Administration. POMS HI 00805.386 – Exceptional Conditions Special Enrollment Period (SEP) for Formerly Incarcerated
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Centers for Medicare & Medicaid Services. Special Election Issues for Individuals Affected by Declared Emergencies and Disasters
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Centers for Medicare & Medicaid Services. Special Enrollment Periods (SEP) Job Aid
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Medicare.gov. How Much Does Medicare Drug Coverage Cost
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Medicare.gov. Get Ready to Buy
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Centers for Medicare & Medicaid Services. Request for Employment Information
12
Social Security Administration. Sign Up for Medicare Part B Online, by Fax, or by Mail
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Medicare.gov. Joining a Plan