If you are turning 65 while on COBRA, sign up for Medicare during your Initial Enrollment Period. COBRA does not count as active employer coverage for Medicare purposes, so waiting can lock in a Part B late enrollment penalty for life, and your former employer’s plan can end your COBRA the moment Medicare takes effect.
Enroll in Medicare During Your Initial Enrollment Period
Your Initial Enrollment Period is a seven-month window: the three months before your 65th birthday month, your birthday month, and the three months after.1Centers for Medicare & Medicaid Services. Original Medicare (Part A and B) Eligibility and Enrollment If you already collect Social Security, Part A enrollment is automatic at 65.2Social Security Administration. When to Sign Up for Medicare If you don’t, you have to sign up for both Part A and Part B yourself.
Here is the trap. Active workers with employer coverage get a Special Enrollment Period that lets them delay Medicare without penalty. COBRA does not qualify, because you are no longer actively employed by the sponsor of the plan. Your seven-month window is the window, and once it closes without an enrollment, you are looking at a penalty and a wait.
Most people qualify for premium-free Part A based on 40 or more quarters of work history. With 30 to 39 quarters, Part A costs $311 per month in 2026; with fewer than 30, it’s $565.3Centers for Medicare & Medicaid Services. 2026 Medicare Parts A and B Premiums and Deductibles If you have to pay for Part A and enroll late, Medicare adds a 10% surcharge for twice the number of years you delayed.
What a Part B Delay Actually Costs
Miss your Initial Enrollment Period and Medicare adds 10% to your Part B premium for each full 12 months you were eligible but not enrolled. The 2026 standard Part B premium is $202.90 per month. A two-year delay adds a 20% surcharge of $40.58 every month, pushing your premium to $243.50, and that surcharge stays on your bill for as long as you have Part B.4Medicare. Avoid Late Enrollment Penalties
The gap in coverage matters just as much as the penalty. If you miss the Initial Enrollment Period, the next chance to sign up is the General Enrollment Period, January 1 through March 31, with coverage starting the month after you enroll.5Medicare. When Does Medicare Coverage Start? If your COBRA has already ended by then, every doctor’s visit and hospital stay in between is on you.
Your Plan Can End COBRA the Day Medicare Starts
Under 26 U.S.C. ยง 4980B, once you become entitled to Medicare after electing COBRA, your group health plan may terminate your COBRA coverage as of the Medicare start date.6Office of the Law Revision Counsel. 26 U.S. Code 4980B – Failure to Satisfy Continuation Coverage Requirements of Group Health Plans Some administrators cut coverage automatically; others end it at the next billing cycle. Either way, plan on losing the medical portion of COBRA once Medicare begins, and line up your Medicare coverage to start the same month so there is no gap.
One exception runs the other direction. If you were already enrolled in Part A or Part B before your COBRA qualifying event, the plan cannot refuse you COBRA or cancel it because of that existing Medicare enrollment.7U.S. Department of Labor. An Employee’s Guide to Health Benefits Under COBRA Most people turning 65 on COBRA are not in that situation. They elected COBRA after leaving a job and are now approaching Medicare age, which puts them squarely in the first category.
The Medigap Window You Probably Don’t Know About
When you enroll in Part B, a six-month clock starts on your Medigap Open Enrollment Period. During those six months, insurers must sell you any Medigap policy they offer regardless of health history, and they cannot charge more for pre-existing conditions.8Medicare.gov. When Can I Buy a Medigap Policy? After six months, in most states, insurers can deny you or price you based on your medical record.
This deadline catches people who assume they can keep COBRA as a supplement and shop for Medigap later. Part B pays 80% of approved costs after a $283 annual deductible in 2026,3Centers for Medicare & Medicaid Services. 2026 Medicare Parts A and B Premiums and Deductibles and paying a full unsubsidized COBRA premium just to cover the 20% coinsurance is usually a bad trade compared to a Medigap policy or a Medicare Advantage plan. Shop within those six months.
Prescription drug coverage has its own late enrollment penalty. If your employer plan was your source of drug coverage and you’re losing it, enroll in a standalone Medicare Part D plan in the same window.
Keeping COBRA for Dental and Vision
Original Medicare doesn’t cover routine dental care, eye exams for prescription glasses, or hearing aids and fitting exams.9Medicare. What’s Not Covered? If your employer plan included dental or vision, you may be able to continue just those pieces under COBRA after Medicare replaces the medical portion.
Under federal law, each qualified beneficiary has an independent right to elect COBRA for each type of coverage the plan offers, and the Department of Labor treats dental and vision as forms of medical care that beneficiaries can choose to continue.7U.S. Department of Labor. An Employee’s Guide to Health Benefits Under COBRA Whether you can actually carve them out depends on how your former employer structured the plan. If medical, dental, and vision are bundled into a single group health plan, separating them may not be possible. Ask your plan administrator before assuming.
Your Spouse and Dependents Get Their Own 36 Months
Your Medicare enrollment is a separate qualifying event for your spouse and dependent children on your COBRA plan. Even though your own COBRA ends, they can continue their coverage for up to 36 months from the date you became entitled to Medicare.6Office of the Law Revision Counsel. 26 U.S. Code 4980B – Failure to Satisfy Continuation Coverage Requirements of Group Health Plans For a younger spouse who is not yet Medicare-eligible, this is often the difference between continuous coverage and a scramble.
The employer must notify the plan administrator within 30 days of your Medicare enrollment, and your dependents then have 60 days to elect their own continuation coverage. The cost is capped at 102% of the full plan premium.7U.S. Department of Labor. An Employee’s Guide to Health Benefits Under COBRA That 36-month runway usually covers the gap until a spouse finds marketplace coverage or reaches Medicare age.
A Timeline That Keeps You Covered
Three months before your 65th birthday month, your Initial Enrollment Period opens. Sign up for Part A and Part B then, even though you still have COBRA. Enrolling early in the window lets your Medicare coverage begin as soon as your birthday month, which minimizes the overlap where you might be paying for both.
Ask your plan administrator, in writing, whether you can continue dental or vision under COBRA after Medicare replaces the medical coverage. Weigh the COBRA premium for those pieces against standalone dental and vision plans on the private market.
Within the first month of Part B coverage, start shopping Medigap or Medicare Advantage. Your six-month Medigap window closes fast, and the guaranteed-issue protection is not something you can get back. If your employer plan carried your prescription drug coverage, enroll in a Part D plan in the same window to avoid a separate drug-coverage penalty.
Finally, if you have a spouse or dependents on your COBRA plan, make sure they know they have their own 60-day election window after your Medicare enrollment triggers the second qualifying event. That decision is on them, not you, and missing it forfeits up to three years of continuation coverage.