A Medicare Special Enrollment Period reopens your enrollment window after a qualifying life event, and knowing which one is yours, before it closes, can save you a lifetime penalty. The costliest mistake here is quiet: someone retires past 65, takes COBRA, and assumes it holds their Medicare window open. It does not. This guide maps each life event to its window and what to file.
In This Guide
- Key Takeaways
- Which Medicare Special Enrollment Period Is Mine?
- Working Past 65: The 8-Month Window and the COBRA Trap
- Losing Medicaid or Extra Help
- The Five Exceptional-Conditions SEPs
- Changing Your Plan: Move, 5-Star, Plan Exit, Disaster
- What If You Miss Your Medicare Special Enrollment Period?
- Frequently Asked Questions
- Learn More
Which Medicare Special Enrollment Period Is Mine?
Medicare runs on a set calendar of enrollment windows, and Special Enrollment Periods are the exception that certain life events unlock.Centers for Medicare & Medicaid Services. (n.d.). Open Enrollment. medicare.gov. Retrieved Jun 23, 2026, from https://www.medicare.gov/health-drug-plans/open-enrollment Start by finding your situation in the table below, then read the section that matches it for the details and the deadline.
| Your situation | Your SEP | Your window |
|---|---|---|
| You (or your spouse) worked past 65 and that job's coverage is ending | Working-aged Part B SEP | 8 months after the job or coverage ends |
| You lost Medicaid or Extra Help | Exceptional-conditions SEP | 6 months after the loss |
| An employer gave you wrong information about enrolling | Exceptional-conditions SEP | 6 months after you notify Social Security |
| You were released from incarceration | Exceptional-conditions SEP | Through the 12th month after release |
| A declared disaster or emergency kept you from enrolling | Disaster SEP | Through 6 months after the declaration ends |
| You moved out of your plan's service area | Move SEP | The month before through 2 months after the move |
| A 5-star plan is available where you live | 5-star SEP | Once, December 8 through November 30 |
| Your plan is leaving Medicare or your area | Plan-termination SEP | Around the plan's exit |
Working Past 65: The 8-Month Window and the COBRA Trap
This is the SEP that costs families the most, because the trap is invisible until the bill arrives. Here is how it actually works.
If you or your spouse are still working and you have group health coverage from that current employer, you can delay Part B and Part D without penalty and enroll later. When that employment ends, you get an 8-month Special Enrollment Period to sign up for Part B, and the clock starts the month after your employment ends or the employer coverage ends, whichever comes first.Centers for Medicare & Medicaid Services. (n.d.). When can I sign up for Medicare?. medicare.gov. Retrieved Jun 23, 2026, from https://www.medicare.gov/basics/get-started-with-medicare/sign-up/when-can-i-sign-up-for-medicare That timing is the whole ballgame, because COBRA and retiree coverage do not count as current-employer coverage. If you retire, take COBRA for a few months, and wait for COBRA to end before signing up for Part B, your 8-month clock has been running the entire time, and it may have already expired.
One more condition decides whether this SEP even exists for you: the size of the employer. Under Medicare's rules, if the employer has 20 or more employees, the group health plan pays first and Medicare pays second, which is what lets you safely delay Part B and use the SEP later.U.S. Government Publishing Office. (n.d.). 42 CFR 411.172 — Medicare benefits secondary to group health plan benefits (working aged). ecfr.gov. Retrieved Jul 10, 2026, from https://www.ecfr.gov/current/title-42/section-411.172 If the employer has fewer than 20 employees, Medicare generally pays first, so you should enroll during your Initial Enrollment Period rather than count on a working-aged SEP that may not apply.
Why does the timing matter so much? Because missing your Part B window triggers a lifetime penalty. The Part B late-enrollment penalty adds 10% to your monthly premium for each full 12-month period you could have had Part B but did not, and it lasts for as long as you have Part B.Centers for Medicare & Medicaid Services. (n.d.). Avoid late enrollment penalties. medicare.gov. Retrieved Jul 15, 2026, from https://www.medicare.gov/basics/costs/medicare-costs/avoid-penalties Since the 2026 standard Part B premium is $202.90 a month, a two-year gap means paying roughly 20% more, every month, for life.Centers for Medicare & Medicaid Services. (n.d.). Avoid late enrollment penalties. medicare.gov. Retrieved Jul 15, 2026, from https://www.medicare.gov/basics/costs/medicare-costs/avoid-penalties If any of this is unclear for your situation, read what Medicare counts as creditable coverage and our guide to the late-enrollment penalties that follow a missed window.
Losing Medicaid or Extra Help
If you had Medicaid or Extra Help with drug costs and then lost it, two separate things happen, and it helps to keep them apart.
First, losing Medicaid opens an exceptional-conditions SEP that gives you 6 months after the termination to enroll in Part B without a penalty.Office of the Federal Register. (2021). Medicare Program; Implementing Certain Provisions of the Consolidated Appropriations Act, 2021 and Other Revisions to Medicare Enrollment and Eligibility Rules (final rule). federalregister.gov. Retrieved Jun 25, 2026, from https://www.federalregister.gov/documents/2022/11/03/2022-23407/medicare-program-implementing-certain-provisions-of-the-consolidated-appropriations-act-2021-and This is the safety net for people who were covered, lost that coverage at a Medicaid eligibility renewal, and now need to pick up Medicare on their own. Your state's State Health Insurance Assistance Program (SHIP) can help you document the loss and act inside the window.
Second, if you still have Medicaid or Extra Help, you can change your drug coverage far more often than most people can. A 2025 Medicare rule changed the direction of this SEP: it replaced the old once-per-quarter window with a once-per-month one, so people with Medicaid or a low-income subsidy can switch to a standalone Part D drug plan in any month of the year.Centers for Medicare & Medicaid Services. (2025). Contract Year 2025 Medicare Advantage and Part D Final Rule (CMS-4205-F). cms.gov. Retrieved Jun 25, 2026, from https://www.cms.gov/newsroom/fact-sheets/contract-year-2025-medicare-advantage-and-part-d-final-rule-cms-4205-f If you have full Medicaid, a separate monthly window also lets you move into an integrated plan built for people who have both Medicare and Medicaid. To see whether you qualify for that help in the first place, look into Medicare Savings Programs and our guide to Extra Help.
The Five Exceptional-Conditions SEPs
In 2023, Medicare added a set of Special Enrollment Periods for people who missed their enrollment because of something outside their control. They come with no late-enrollment penalty, and coverage begins the first day of the month after you enroll. There are five, and each has its own window:
- You lost Medicaid. A 6-month SEP starting when your Medicaid eligibility ends.
- An employer or health plan gave you wrong information. A 6-month SEP starting the day you notify Social Security that misinformation caused you to miss enrolling.
- You were released from incarceration. An SEP that runs through the last day of the 12th month after the month you were released.
- A declared emergency or disaster affected you. An SEP that ends 6 months after the declaration's end date, meant for people a disaster kept from acting during another enrollment window.
- Another exceptional condition. A catch-all that Medicare decides case by case, lasting at least 6 months, for situations the other four do not name.Office of the Federal Register. (2021). Medicare Program; Implementing Certain Provisions of the Consolidated Appropriations Act, 2021 and Other Revisions to Medicare Enrollment and Eligibility Rules (final rule). federalregister.gov. Retrieved Jun 25, 2026, from https://www.federalregister.gov/documents/2022/11/03/2022-23407/medicare-program-implementing-certain-provisions-of-the-consolidated-appropriations-act-2021-and
These SEPs were created by the Consolidated Appropriations Act, 2021 (the BENES Act) and are written into the rules at 42 CFR 407.23. To use one, you apply for the special enrollment through the Social Security Administration; if your situation is not one of the four named categories, be ready to explain why it was genuinely exceptional.
Changing Your Plan: Move, 5-Star, Plan Exit, Disaster
The SEPs above are mostly about getting into Medicare on time. A second group is for people already in Medicare who need to change a Medicare Advantage or Part D plan between the regular enrollment periods.Centers for Medicare & Medicaid Services. (n.d.). Special Enrollment Periods. medicare.gov. Retrieved Jun 25, 2026, from https://www.medicare.gov/basics/get-started-with-medicare/get-more-coverage/joining-a-plan/special-enrollment-periods
- You moved out of your plan's service area. If you tell your plan before you move, your window to switch begins the month before the move and runs 2 full months after; if you tell them after, it begins the month you move and runs 2 full months after.
- A 5-star plan is available near you. You can switch into a 5-star-rated Medicare Advantage, Part D, or Cost plan once, any time from December 8 of the prior year through November 30 of the plan year. Our guide to Medicare star ratings explains what the rating means.
- Your plan is leaving. If your plan's contract with Medicare is not renewed or it pulls out of your area, you get a window to move to another plan.
- A disaster or emergency got in your way. If a federal, state, or local government declares an emergency or disaster that kept you from acting during another enrollment period, you may get an SEP to join, switch, or drop a plan.
For any of these plan changes, your new coverage generally starts the first day of the month after your plan gets your request.Centers for Medicare & Medicaid Services. (n.d.). Open Enrollment. medicare.gov. Retrieved Jun 23, 2026, from https://www.medicare.gov/health-drug-plans/open-enrollment
What If You Miss Your Medicare Special Enrollment Period?
If no SEP applies and you missed your Initial Enrollment Period, your fallback is the General Enrollment Period, which runs January 1 through March 31 each year.Centers for Medicare & Medicaid Services. (n.d.). When can I sign up for Medicare?. medicare.gov. Retrieved Jun 23, 2026, from https://www.medicare.gov/basics/get-started-with-medicare/sign-up/when-can-i-sign-up-for-medicare Coverage from a General Enrollment Period sign-up now begins the first day of the month after you enroll, and a late-enrollment penalty may apply.Centers for Medicare & Medicaid Services. (n.d.). When can I sign up for Medicare?. medicare.gov. Retrieved Jun 23, 2026, from https://www.medicare.gov/basics/get-started-with-medicare/sign-up/when-can-i-sign-up-for-medicare For prescription drugs, going without creditable coverage adds 1% of the national base beneficiary premium (which is $38.99 in 2026) for each month you went without, for as long as you have Part D.Centers for Medicare & Medicaid Services. (n.d.). Avoid late enrollment penalties. medicare.gov. Retrieved Jul 15, 2026, from https://www.medicare.gov/basics/costs/medicare-costs/avoid-penalties If you are trying to sort out the regular calendar rather than a life-event window, our overview of Medicare enrollment periods walks through all of them.
Frequently Asked Questions
Does COBRA count for a Medicare Special Enrollment Period?
No. COBRA and retiree coverage do not count as current-employer coverage, so they do not extend your 8-month Part B window. The clock starts when your active employment or employer coverage ends, not when COBRA ends. Enroll in Part B based on the job ending, even if you keep COBRA for other reasons.
How long is the working-past-65 Special Enrollment Period?
Eight months, starting the month after your (or your spouse's) employment ends or the employer coverage ends, whichever comes first. That assumes the employer had 20 or more employees; at a smaller employer, Medicare usually pays first and you should enroll during your Initial Enrollment Period.
I just lost Medicaid. What is my Medicare deadline?
You have a 6-month exceptional-conditions Special Enrollment Period, starting when your Medicaid ends, to enroll in Part B with no late penalty. If you still have Medicaid or Extra Help, you can also switch your standalone drug plan once a month.
Can I switch Medicare plans after I move?
Yes. Moving out of your plan's service area opens a Special Enrollment Period. If you notify your plan before the move, it runs from the month before through 2 months after; if you notify them after, it runs from the month you move through 2 months after.
What happens if I miss my window entirely?
You generally wait for the General Enrollment Period (January 1 through March 31), your coverage starts the first of the month after you sign up, and a lifetime late-enrollment penalty may apply to Part B and Part D.
Learn More
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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.