Medicare · Cornerstone
Working past 65, Medicare, COBRA, and the SEP trap
Last reviewed June 11, 20263 min readBy the Goodsurance editorial team Reviewed by the Goodsurance editorial team
More people are working past 65 than ever, and Medicare's rules were built around an assumption that everyone retires at 65, so the two do not line up cleanly. The result is a handful of traps that catch otherwise careful people. This page is the still-working playbook: when it is safe to wait, what does and does not protect you, and how to land the transition when you finally retire.
1When waiting is the right move
If you are working at an employer with 20 or more employees and you have good coverage through that job, you can generally delay Part B without penalty and enroll later when you retire. For many people this is the financially sensible choice, because paying a Part B premium on top of employer coverage you are already paying for is often money spent twice for overlapping coverage. Most people in this situation still take premium-free Part A, with the HSA exception below.
The reason this is safe is the Special Enrollment Period: large-employer coverage based on current work keeps your enrollment window open, so you are not penalized for waiting. The key words are "20 or more" and "current employment." Change either and the calculus changes.
2The HSA trap
This is the trap that surprises high earners and diligent savers most, because it punishes a good habit. If you contribute to a Health Savings Account through a high-deductible health plan at work, enrolling in any part of Medicare, including premium-free Part A, ends your eligibility to contribute to that HSA. You can still spend the money already in the account, but you cannot add to it.
Two consequences follow. First, if you want to keep funding your HSA past 65, you may need to delay even free Part A. Second, because Part A enrollment can be backdated up to six months when you eventually sign up, you should stop HSA contributions several months before you enroll in Medicare or claim Social Security, to avoid an overlap that creates a tax problem.
Enrolling in any part of Medicare, including free Part A, ends HSA contributions. And Part A enrollment can backdate up to six months, so stop contributing several months before you enroll or claim Social Security, to avoid a tax problem from the overlap.
3The COBRA trap
COBRA feels like a safety net, and for Medicare purposes it is not the one you think. COBRA is not considered active, current-employment coverage, so it does not protect your Part B enrollment window. If you leave a job at or after 65 and rely on COBRA instead of enrolling in Medicare, your enrollment clock may already be running, and waiting can leave you with both a coverage gap and a lifelong Part B penalty. If you are 65 or older and leaving a job, you usually want to enroll in Medicare rather than treat COBRA as a substitute. The same caution applies to retiree coverage from a former employer.
- Not active, current-employment coverage
- Does not protect your Part B window
- From a former employer
- Also does not protect the window
4Landing the transition: the Special Enrollment Period
When your employment or your employer coverage ends, you get a Special Enrollment Period to sign up for Part B without penalty, generally up to eight months. The mistake people make is treating eight months as breathing room. The penalty protection lasts that long, but your coverage does not start until you enroll, so if you wait, you can be uninsured in the meantime. The clean transition is to enroll in Part B in the month before your employer coverage ends, so Medicare picks up the day the group plan stops. If you are also adding a Medigap supplement or a drug plan, line those up in the same window.
Protection is not coverage
Common questions about Medicare
Quick answers to common questions
Tap any question to expand. Each question links to a fuller standalone answer.
Do I need Medicare if I'm still working at 65?
Not necessarily; whether you need Medicare at 65 while working depends on your employer's size and your coverage.
If you have active health coverage through a job with 20 or more employees, where you or your spouse still work, you can usually delay Part B (medical) without penalty and enroll later through a Special Enrollment Period. If your employer has fewer than 20 employees, Medicare often becomes the primary payer, so signing up at 65 usually makes sense to avoid coverage gaps. Many people still enroll in premium-free Part A (hospital) at 65 even while working, though that choice interacts with health savings accounts. To weigh whether to take Medicare now or delay, reach out to a licensed Goodsurance advisor at 1-888-301-8091 (TTY 711), Mon to Fri 8 am to 5 pm PT.
Can I delay Medicare past 65?
Yes, you can delay Medicare past 65 without a penalty if you have qualifying coverage, usually active health insurance through a job with 20 or more employees, where you or your spouse still work.
In that case, you can sign up later through a Special Enrollment Period, which gives you 8 months after that employment or coverage ends, whichever comes first, to enroll in Part B (medical) without a late penalty. The 20-employee rule is what decides whether delaying is safe: at smaller employers, Medicare often pays first, so delaying can leave gaps and trigger a penalty. Retiree coverage, COBRA, and marketplace plans do not count as qualifying coverage for delaying. To confirm whether you can safely delay, reach out to a licensed Goodsurance advisor at 1-888-301-8091 (TTY 711), Mon to Fri 8 am to 5 pm PT.
Can I contribute to an HSA if I have Medicare?
No, you cannot contribute to a health savings account (HSA) once you have any part of Medicare, including premium-free Part A (hospital).
An HSA is a tax-advantaged account paired with a high-deductible health plan, and IRS rules say enrollment in any Medicare coverage ends your eligibility to make new contributions. This catches many people who keep working past 65, because if you sign up for Social Security, you are usually enrolled in Part A automatically, which stops HSA contributions. You can still use money already in your HSA for qualified expenses; you just cannot add more. People who want to keep contributing sometimes choose to delay both Social Security and Part A while they keep working. To plan the timing so you do not lose contributions by surprise, reach out to a licensed Goodsurance advisor at 1-888-301-8091 (TTY 711), Mon to Fri 8 am to 5 pm PT.
What is the Special Enrollment Period for working past 65?
The Special Enrollment Period is a window that lets you enroll in Medicare after 65 without a late penalty if you delayed because you had active employer coverage.
It applies when you or your spouse worked and had qualifying coverage through a job, generally one with 20 or more employees. Once that employment or coverage ends, whichever comes first, you get 8 months to sign up for Part B (medical) without a penalty. Acting within that 8-month window matters, because waiting past it can leave you with a coverage gap and a permanent Part B late penalty. Retiree coverage, COBRA, and marketplace plans do not start this Special Enrollment Period. To make sure you use your window correctly, reach out to a licensed Goodsurance advisor at 1-888-301-8091 (TTY 711), Mon to Fri 8 am to 5 pm PT.
When can I enroll in Medicare?
Most people can first enroll in Medicare during their Initial Enrollment Period, a seven-month window around your 65th birthday that starts three months before the month you turn 65, includes that month, and ends three months after.
If you miss it, the General Enrollment Period runs January 1 to March 31 each year for Part A and Part B. After you have Medicare, the Annual Enrollment Period from October 15 to December 7 (2026) lets you change Part D drug plans and Medicare Advantage plans, with changes effective January 1. The Medicare Advantage Open Enrollment Period from January 1 to March 31 (2026) lets people already in a Medicare Advantage plan switch once. Special Enrollment Periods may also apply after certain life events, like losing job coverage. To review which window fits you, reach out to a licensed Goodsurance advisor at 1-888-301-8091 (TTY 711), Mon to Fri 8 am to 5 pm PT.
What is AEP in Medicare?
AEP stands for the Annual Enrollment Period, the yearly window when anyone with Medicare can make changes to their coverage.
It runs from October 15 to December 7 (2026), and the changes you make take effect January 1 of the following year. During AEP you can join, switch, or drop a Medicare Advantage plan (Part C), join, switch, or drop a Part D prescription drug plan, and move between Original Medicare and Medicare Advantage. This is the main once-a-year opportunity to review your plan against your current doctors, medications, and budget, since plans can change their costs and coverage each year. AEP is different from the Medicare Advantage Open Enrollment Period, which runs January 1 to March 31 (2026) and only lets people already in a Medicare Advantage plan make one switch. If you want to change plans, AEP is usually the time to do it.
What is the Medicare Open Enrollment Period?
The term Medicare Open Enrollment Period is used two ways, so it helps to be specific.
Most often people mean the Annual Enrollment Period (AEP), which runs October 15 to December 7 (2026) and lets anyone with Medicare join, switch, or drop a Medicare Advantage plan (Part C) or a Part D drug plan, with changes effective January 1. Separately, the Medicare Advantage Open Enrollment Period runs January 1 to March 31 (2026) and lets people already enrolled in a Medicare Advantage plan make one change, such as switching to another Medicare Advantage plan or returning to Original Medicare. There is also a Medigap Open Enrollment Period, a six-month window that begins when you are 65 or older and enrolled in Part B, during which you can buy a Medigap (supplement) policy without health-based pricing. Knowing which one you mean determines what you can change.
Can I change my Medicare Advantage plan in January?
Yes.
If you are already in a Medicare Advantage plan (Part C, your Medicare benefits through a private plan), the Medicare Advantage Open Enrollment Period lets you make one change between January 1 and March 31 (2026). During this window you can switch to a different Medicare Advantage plan, or leave Medicare Advantage and return to Original Medicare, and if you return to Original Medicare you can also add a Part D drug plan. This window is only for people who already have a Medicare Advantage plan on January 1; it is not a time to switch from Original Medicare into Medicare Advantage. You get one change during this period, and it takes effect the first of the month after the plan receives your request. This is separate from the Annual Enrollment Period, which runs October 15 to December 7 (2026). If you missed making a change during AEP, the January to March window is a second chance for current Medicare Advantage members.
How do I sign up for Medicare?
You sign up for Medicare through Social Security, online at ssa.gov, by phone, or in person at a Social Security office; Medicare itself does not handle enrollment.
The best time is your Initial Enrollment Period, the seven-month window around your 65th birthday. If you already receive Social Security benefits, you are usually enrolled automatically in Part A and Part B. If you are not yet drawing Social Security, you have to apply yourself. After you have Part A and Part B, you can separately choose added coverage like a Part D drug plan, a Medicare Advantage plan, or a Medigap supplement. To talk through which added coverage fits your situation, reach out to a licensed Goodsurance advisor at 1-888-301-8091 (TTY 711), Mon to Fri 8 am to 5 pm PT.
Is Medicare automatic at 65?
Medicare is not automatic for everyone at 65; it depends on whether you already receive Social Security.
If you are drawing Social Security or Railroad Retirement benefits before 65, you are usually enrolled automatically in Part A (hospital) and Part B (medical), and your card arrives a few months before your birthday. If you have not started those benefits, enrollment is not automatic, and you must apply yourself through Social Security during your Initial Enrollment Period, the seven-month window around your 65th birthday. People who qualify through disability are often enrolled automatically after 24 months of benefits. Even when Part A and B are automatic, drug coverage and other plan choices are not. To review your options, reach out to a licensed Goodsurance advisor at 1-888-301-8091 (TTY 711), Mon to Fri 8 am to 5 pm PT.
Where do I enroll in Medicare?
You enroll in Medicare through the Social Security Administration, not through Medicare directly.
You can apply online at ssa.gov, by phone, or in person at a local Social Security office. Railroad retirees apply through the Railroad Retirement Board instead. This applies to Part A (hospital) and Part B (medical). Added coverage works differently: you enroll in a Part D drug plan, a Medicare Advantage plan, or a Medigap supplement through the insurance company offering it or with help from a licensed agent, not through Social Security. Knowing which door to use saves time and helps avoid gaps. To get help choosing and enrolling in added coverage, reach out to a licensed Goodsurance advisor at 1-888-301-8091 (TTY 711), Mon to Fri 8 am to 5 pm PT.
Do I need to sign up for Medicare if I have other insurance?
It depends on the kind of other insurance you have.
If you have active employer coverage through a job with 20 or more employees, where you or your spouse still work, you can usually delay Medicare without penalty and sign up later through a Special Enrollment Period. If your employer has fewer than 20 employees, Medicare often becomes the primary payer, so you typically need to enroll at 65 to avoid gaps. Retiree coverage, COBRA, and marketplace plans generally do not count as active employer coverage, so delaying Medicare with those can trigger a late penalty. The rules turn on whether the coverage is active and the employer's size. To check your specific situation, reach out to a licensed Goodsurance advisor at 1-888-301-8091 (TTY 711), Mon to Fri 8 am to 5 pm PT.
References
- Medicare.govWorking past 65, the Special Enrollment Period, and COBRA's role.
- IRS, Internal Revenue ServiceHSA contribution rules and Medicare enrollment timing. irs.gov
- SSA, Social Security AdministrationPart A retroactivity and enrollment. ssa.gov