In short
- There are two kinds: Special Enrollment Periods for Part A and Part B (handled by Social Security) and ones for Medicare Advantage and Part D (handled by plans).
- Ending current employer coverage gives you 8 months to get Part B without a penalty, but only 2 full months to join a drug or Medicare Advantage plan.
- COBRA and retiree coverage do not count as current employment coverage for the Part B Special Enrollment Period.
- The employer Part B SEP is proved with Form CMS-L564, sent with the CMS-40B application to Social Security.
- If your Medicare Advantage plan leaves your county, you get a window to choose a new plan and may get a guaranteed right to buy Medigap.
A Special Enrollment Period (SEP) is a window Medicare opens when something specific happens in your life, like losing job-based coverage, moving, or your plan leaving your area. It lets you sign up for Medicare or change plans outside the usual dates, usually without a late penalty. The catch: each one has its own deadline, and you may need to prove the event.
There are two separate families of Special Enrollment Periods. One is for signing up for Part A and Part B, which goes through Social Security. The other is for joining or changing Medicare Advantage and Part D plans, which goes through the plans.
Which Special Enrollment Periods let you sign up for Part B late?
The main one is for people who had coverage through a current job. If you had group health coverage based on your own or your spouse's current employment (or a family member's, if you are disabled), you can sign up for Part A and Part B:
- Any time while you still have that coverage, or
- During the 8 months that begin the month after the employment ends or the coverage ends, whichever happens first
COBRA, retiree plans, VA coverage, individual Marketplace plans and severance coverage do not count as current employment coverage. The 8-month clock starts when the job ends, whether or not you take COBRA. That trips up a lot of people; see COBRA vs Medicare.
Medicare also has exceptional condition SEPs, added January 1, 2023, for people who missed a sign-up because of situations outside their control:
- You lost Medicaid coverage
- A natural disaster or emergency kept you from signing up
- Your employer or health plan gave you inaccurate information
- You were released from incarceration
- Other exceptional situations Medicare approves
There are also SEPs tied to TRICARE and to volunteer service outside the U.S. For any exceptional condition, contact Social Security, because the time limits differ by situation.
How do you prove employer coverage for the Part B SEP?
You use two forms and send them to Social Security:
- CMS-40B, the Application for Enrollment in Medicare Part B.
- CMS-L564, the Medicare Request for Employment Information. You fill out Section A. Your employer fills out Section B: whether you were covered by its group health plan, the coverage start and end dates, and the dates you worked there.
Mail or fax both to your local Social Security office. Per the form's instructions, to qualify you must have had group coverage through current employment since the first month you were eligible for Part B, and that coverage must not have ended more than 8 months ago.
Our guide to working past 65 covers the employer-size rules that decide whether you can delay Part B at all.
Which Special Enrollment Periods let you join or change a plan?
These SEPs apply to Medicare Advantage and Part D plans. The table lists the ones people use most, with timing from Medicare's enrollment period fact sheet.
| Your situation | What you can do | How long you have |
|---|---|---|
| Leaving employer or union coverage (including COBRA) | Join a Medicare Advantage or Part D plan | 2 full months after the month coverage ends |
| Moving out of your plan's service area | Switch plans, or go back to Original Medicare | From the move through 2 full months after (starts a month earlier if you tell the plan first) |
| Moving within the area with new plan options | Switch plans | Same as above |
| Moving back to the U.S. | Join a plan | 2 full months after the month you return |
| Losing creditable drug coverage through no fault of your own | Join a plan with drug coverage | 2 full months after you lose it or are told it is no longer creditable, whichever is later |
| Losing Medicaid | Join, switch or drop plans | 3 full months from the date you lose eligibility or are notified, whichever is later |
| Medicaid or Extra Help | Join or switch Part D plans; leave Medicare Advantage for Original Medicare plus Part D | Once per calendar month |
| Full Medicaid and an integrated D-SNP is available | Join or switch to the integrated plan | Once per calendar month |
| Losing Extra Help for next year | Join, switch or drop plans | 3 full months from the date you are no longer eligible or notified |
| Moving into or out of a nursing home or rehab facility | Join, switch or drop plans | While you live there and 2 full months after you leave |
| Released from incarceration | Join a plan | 2 full calendar months after release |
| A 5-star plan is available | Join it, once | December 8 of the prior year through November 30 |
| Your plan has been under 3 stars for 3 years in a row | Switch plans | Any time while you are in that plan |
| Your plan's contract isn't renewed | Switch plans | December 8 through the last day of February |
| Medicare ends your plan's contract | Switch plans | 1 month before through 2 full months after the contract ends |
| First year in Medicare Advantage after joining at 65 | Drop it for Original Medicare | 12 months after joining |
The monthly Medicaid and Extra Help windows replaced an older quarterly SEP for enrollments starting in 2025. They are not available to people a plan has flagged as "at-risk" under a Part D drug management program. Star Ratings, and how to find the 5-star plans, are explained in Medicare Star Ratings.
How do you prove a Special Enrollment Period?
For plan SEPs, the enrollment form asks you to check the reason you qualify and give the date of the event. The plan or Medicare can ask for proof, so keep a paper trail:
- Lost employer coverage: a letter from the employer or plan with the coverage end date, or a COBRA notice
- Lost creditable drug coverage: the notice saying your coverage is ending or no longer creditable (employer plans must tell you each year whether their drug coverage is creditable)
- Moved: something showing your new address and move date
- Lost Medicaid or Extra Help: the termination or non-eligibility letter from Nebraska DHHS or Social Security
- Plan leaving your area: the plan's non-renewal or termination notice
Medicare's Medigap guide also advises keeping the postmarked envelope a notice came in, as proof of when it was mailed. Store these with your Medicare card paperwork.
What if your Medicare Advantage plan leaves your Nebraska county for 2027?
Several companies are shrinking their Nebraska service areas for 2027, according to CMS landscape data. Medica's Medicare Advantage plans leave eight eastern counties, including Lancaster, Douglas and Sarpy. UnitedHealthcare's AARP Medicare Advantage plans with drug coverage drop from 52 counties to 5. Blue Cross and Blue Shield of Nebraska drops from 76 counties to 61. If your plan is affected, you should have received a notice.
What that means for you:
- Pick a new plan during Annual Enrollment (October 15 to December 7, 2026) so coverage starts January 1, 2027.
- If you miss it, the non-renewal SEP runs December 8 through the last day of February. If you do nothing, you are moved to Original Medicare when the old plan ends.
- If you choose Original Medicare instead, you have a guaranteed issue right to buy Medigap Plan A, B, D or G (C or F if you were eligible before 2020) with no health questions. You can apply up to 60 days before the plan ends and no more than 63 days after.
Plan availability, premiums, networks and benefits vary by county and change every year. See Medigap open enrollment in Nebraska for the guaranteed issue details.
Where can you get help with a Special Enrollment Period?
For Part A and Part B SEPs, contact Social Security at 1-800-772-1213. For plan SEPs, call 1-800-MEDICARE (1-800-633-4227), available 24 hours a day, 7 days a week (TTY 1-877-486-2048). Nebraska SHIP (1-800-234-7119) gives unbiased counseling at no cost. A licensed agent can check whether you qualify and help you enroll; talk to Bill if you want a local person to sort out the dates with you. For every other window, see all Medicare enrollment periods.
Frequently asked questions
If you had group health coverage based on your or your spouse's current employment, you have 8 months starting the month after the employment or the coverage ends, whichever happens first. Taking COBRA does not extend that clock. For drug coverage, the window is shorter: you have 2 full months after the month your employer coverage ends to join a Part D or Medicare Advantage plan without a penalty.
It is the Medicare Request for Employment Information. You fill out Section A, and your employer fills out Section B with the dates you had group health coverage and the dates you worked there. You mail or fax it to your local Social Security office along with Form CMS-40B, the Application for Enrollment in Medicare Part B. It proves you qualify for the Part B Special Enrollment Period.
It can. If you move out of your current plan's service area, you can switch plans from the month you move through 2 full months after. If you tell your plan before you move, the window starts the month before the move. If you move within the service area but have new plan options at the new address, you also qualify. Plan service areas in Nebraska are county-based.
Yes. If a Medicare Advantage plan, Medicare Cost Plan or Part D plan with an overall 5-star rating is available where you live, you can join it once between December 8 of the year before and November 30 of the plan year. For 2027 plans, that runs December 8, 2026 to November 30, 2027. CMS expects to post 2027 Star Ratings on Medicare.gov on or around October 8, 2026.
Keep anything dated that shows the event: a letter from your employer with your coverage end date, your plan's termination or non-renewal notice, a Medicaid termination letter, a notice that your drug coverage is no longer creditable, or proof of a new address. Medicare's Medigap guide also recommends keeping the postmarked envelope as proof of when a notice was mailed.
Yes. Since 2025, people with Medicaid or Extra Help can join or switch standalone Part D plans once per calendar month, or leave a Medicare Advantage plan with drugs for Original Medicare plus a standalone Part D plan. People with full Medicaid can also join an integrated Dual Eligible Special Needs Plan once a month. Changes start the first day of the next month.
Sources
- Medicare.gov: Understanding Medicare Advantage and drug plan enrollment periods (11219) (opens in a new tab)
- Medicare.gov: When does Medicare coverage start? (opens in a new tab)
- CMS Form CMS-L564: Medicare Request for Employment Information (opens in a new tab)
- Medicare & You 2027 handbook (CMS Product 10050) (opens in a new tab)
- Medicare.gov: Choosing a Medigap Policy (02110) (opens in a new tab)
- CMS: CY 2025 Medicare Advantage and Part D final rule fact sheet (opens in a new tab)
We do not offer every plan available in your area. Any information we provide is limited to those plans we do offer in your area. Please contact Medicare.gov or 1-800-MEDICARE to get information on all of your options. 1-800-MEDICARE (1-800-633-4227) is available 24 hours a day, 7 days a week. TTY users can call 1-877-486-2048.
