COBRA and Medicare Part B Do Not Share a Deadline

COBRA can keep an employer health plan in place for a limited time after a job ends, or after a spouse or dependent loses that coverage [1]. It does not, by itself, count as employer coverage based on current employment [2]. Because of that, COBRA and Medicare Part B do not share a deadline. The special enrollment period tied to an active job does not restart when COBRA ends, and electing COBRA does not push that period out [2][4].

What COBRA continues, and what it does not

The Consolidated Omnibus Budget Reconciliation Act is a federal law. It may let you keep employer or union group health plan coverage for a limited time after employment ends, or after you lose coverage as a spouse or dependent of the covered employee [1][3]. Medicare calls that arrangement continuation coverage [3].

In general, federal COBRA applies to employers with 20 or more employees [1]. Some states require insurers covering smaller employers to offer continuation for a limited time, and Medicare says to ask the state insurance commissioner's office whether that coverage is available [1]. The plan administrator is the right person to say which kind of notice you received. For Part B, the question that matters is whether the coverage is based on current employment.

COBRA is generally offered for 18 months, and for 36 months in some cases [1]. Those lengths belong to the health plan, not to the time Medicare gives you to enroll in Part B without a penalty. An 18-month offer can outlast the Part B window. That gap is what we walk through with families in Greensboro and the rest of the Piedmont after a retirement, a layoff, or a spouse's job change.

Active employer or union coverage does not include COBRA, retiree coverage, VA coverage, individual Marketplace coverage, or coverage from severance or a layoff [2]. A card that still shows the old employer name can be any of those. The name on the card is not the test.

Active work is the coverage that can delay Part B

There is a real Part B special enrollment period, and it is useful when it fits. People age 65 or older who did not enroll in Part B when first eligible can enroll later, without a penalty, if they or a spouse is currently working and they have employer or union group health plan coverage based on that employment [5]. You may sign up any time that current-employment coverage is still in place, or for up to 8 months after the group health plan coverage or the employment ends, whichever happens first [5].

We explain that still-working path, including when employer size changes who pays the bill, in our guide to working past 65 with employer coverage in North Carolina. This article is only the contrast. COBRA is what often starts after that current employment ends.

CMS states the limit directly. COBRA and retiree health plans are not coverage based on current employment, and people with that coverage are not eligible for this special enrollment period when it ends [5]. The handbook agrees: COBRA does not make you eligible for a special enrollment period when it ends, and retiree plans and VA coverage are treated the same way [2]. The 8-month period starts when you stop working, even if you choose COBRA [8]. Getting COBRA does not change that end date [4]. The end of COBRA, the end of retiree coverage, and a missed 8-month window after work or job-based coverage stops are all situations that do not qualify for a Part B special enrollment period [4].

A stipend to buy Marketplace coverage is not group health plan coverage for this special enrollment period [5]. A Small Business Health Options Program (SHOP) plan can be, when you have it because of your own current work or a spouse's current work [5]. If Medicare comes from a disability, CMS allows this period when you, a spouse, or a family member is working and the plan is a large group health plan with at least 100 employees [5]. This period does not apply if you are eligible for Medicare because of End-Stage Renal Disease, or while you are still in your Initial Enrollment Period [2].

Two timelines that should not be mixed

The job is ending, and COBRA is the offer that follows. Delaying Part B can be allowed while coverage is based on your current job or a spouse's current job [5]. The 8 months still start when that employment or that group coverage ends, whichever happens first, whether or not you elect COBRA [2][8]. Suppose the active plan ends on the last day of June and COBRA would run many months after that. Part B is timed from the end of the job-based plan, not from the last COBRA month [2][4]. If you want Medicare to start as that job plan ends, sign up the month before you or your spouse plan to retire. Coverage starts the month after Social Security, or the Railroad Retirement Board, gets the completed forms, including the form that shows the job-based coverage [8].

You are already on COBRA when you turn 65. That is not the still-working rule. If COBRA started after the job ended, or after you lost coverage as a dependent, and you have not signed up for Medicare, sign up when you turn 65 to avoid a gap and a monthly Part B late enrollment penalty [9]. COBRA you had before Medicare will probably end once you sign up, and waiting for COBRA to finish does not extend the time to enroll in Part B [1][9].

You already have Medicare, and then the job ends. If you got COBRA after you signed up for Medicare, COBRA pays after Medicare, unless you have End-Stage Renal Disease [9]. Keeping the continuation plan is then a question of extra benefits and cost. It is not a way to postpone Part B, because Part B is already in place.

A spouse is the employee. The special enrollment period can rest on a spouse who is currently working and on group coverage from that job [5]. It cannot rest on a spouse's COBRA [2][5]. If your spouse keeps working and you stay on the active plan, use the still-working guide linked above. If the job-based plan ends before either of you stops working, the 8 months still run from that loss of coverage [8]. A cut in hours can start the Part B period in the same week the COBRA notice arrives.

Who pays if Part B is missing

While you are 65 or older and the plan is based on current employment, size still matters. If the employer has 20 or more employees, or fewer than 20 but is in a multi-employer group where at least one company has 20 or more, the group plan generally pays first and Medicare pays second [3]. If the employer has fewer than 20 and is not in a group like that, Medicare pays first [3]. That current-job rule is why some people at larger employers can delay Part B, and why some people at small employers should not. It does not apply to COBRA.

Once Medicare and COBRA are both in force, the order is simpler for most people. If you have Medicare because you are 65 or older, or because you have a disability, Medicare pays first [3]. End-Stage Renal Disease is the exception in that booklet. If you are eligible because of End-Stage Renal Disease, COBRA pays first and Medicare pays second during a coordination period of up to 30 months after you are first eligible, and Medicare pays first after that period [3].

If you have COBRA and you are eligible for Medicare but not enrolled, COBRA may pay only a small portion of your care, and you may have to pay most of the cost yourself [1]. CMS tells employers that taking COBRA instead can leave a person with significant bills, and that eligible people should sign up as soon as employment ends [11]. Missing that chance can mean a life-long Part B late enrollment penalty, because the end of COBRA does not qualify for the group-health-plan special enrollment period [11]. The next broad chance is the General Enrollment Period, from January 1 through March 31 each year, with coverage starting the month after you sign up [1][4]. How that penalty is calculated is in our guide to the Medicare Part B late enrollment penalty. Ask the COBRA plan what share it will pay if you are eligible and not enrolled [1].

The COBRA election period, the Part B enrollment period, and the Medigap Open Enrollment Period can have different deadlines, and a choice about one coverage can cause you to lose rights under another [3].

Drug coverage is a separate, shorter chance

If you leave employer or union coverage, including COBRA, you may join a Medicare Advantage plan or a Medicare drug plan [7]. That chance lasts for 2 full months after the month the coverage ends [7]. Joining a Medicare Advantage plan requires both Part A and Part B [4]. Joining a stand-alone drug plan requires Part A or Part B [4]. The 2-month chance does not enroll you in Part B, and it does not reopen an 8-month Part B period you have already missed.

Drug coverage inside the COBRA plan can still be useful. If that coverage is creditable prescription drug coverage, you have a special enrollment period to join a Medicare drug plan without a penalty when COBRA ends [2][3]. If you are not sure it counts, ask the plan. The plan has to tell you, and it sends that information each year, so keep the notice [9]. You will not pay the Part D late enrollment penalty as long as you do not go more than 63 days without creditable drug coverage [9].

Call the benefits administrator before you add Medicare drug coverage. Medicare & You warns that getting Medicare drug coverage may cause you to lose employer or union health coverage [2].

How to enroll while the job-based window is open

If you already have Part A and you are using the job-based special enrollment period to add Part B, Medicare directs you to Social Security, including the option to fax or mail forms to a local office [4]. The Part B application, when you already have Part A, is CMS-40B. The proof of employer coverage is CMS-L564, Request for Employment Information [6].

The L564 instructions say you must have, or have had, group health plan coverage within the last 8 months through your current employment or a spouse's current employment [6]. People using the period because of a disability must have large group health plan coverage based on their own, a spouse's, or a family member's current employment [6]. You complete the first section. The employer completes the coverage and employment dates and signs. You send that form in with CMS-40B [6].

The form proves coverage based on current employment, which COBRA is not [2][6]. Continuation coverage is often available for 18 months, which is longer than the last 8 months of current employment the form asks you to show [1][6]. If you wait until COBRA runs out, the employer may no longer be able to certify those active-job dates.

Part B generally starts on the first day of the month after you sign up [2]. If you sign up while you or your spouse are still working, or within the first full month after employer coverage ends, you can ask to delay that start by up to 3 months [2][4]. That is not extra time from electing COBRA. If you are still in the 7-month Initial Enrollment Period around your 65th birthday, use that period [4]. The job-based special enrollment period comes only after it, and only when current employment is why you waited [2].

Who can help you read the notice

Questions about your own COBRA options go to the employer's benefits administrator [1]. For a free review that is not a sales call, North Carolina's Seniors' Health Insurance Information Program, called SHIIP, counsels Medicare beneficiaries and caregivers and offers free, unbiased information [10]. SHIIP counselors are not licensed insurance agents, and they do not sell or endorse any product, plan, or company [10]. They serve every county, with local counseling by appointment [10]. The SHIIP toll-free line is 1-855-408-1212, on weekdays from 8 am to 5 pm [10].

If the question is which insurance should pay a claim, Medicare lists the Benefits Coordination and Recovery Center at 1-855-798-2627 (TTY 1-855-797-2627) [1].

Practical takeaways

• COBRA continues a health plan for a limited time. It is not coverage based on current employment, and the end of COBRA does not open a Part B special enrollment period [2][5].
• If you had group coverage from current work, you have up to 8 months after that employment or that coverage ends, whichever happens first, whether or not you take COBRA [2][8].
• If you are already on COBRA and have not signed up for Medicare, sign up when you turn 65 rather than waiting for the continuation plan to finish [9].
• If you are eligible for Medicare and not enrolled, the COBRA plan may pay only a small share of the bill [1].
• The chance to join a Medicare Advantage plan or a drug plan after COBRA ends is a separate, shorter window, and an Advantage plan still requires Part B [4][7].
• Have the employer complete Form CMS-L564 while current-employment coverage is still inside the last 8 months the form describes, and keep any notice that says the drug coverage is creditable [6][9].

How we can help

Have more questions or want to get in touch? Our team at Seniors Insurance Hub helps people in Greensboro and the Piedmont, including adult children sorting this out for a parent, time Part B when a job is ending and a COBRA election is on the table. You can reach us through our contact page.

You can reach our Greensboro office at (336) 937-7501.

Citations

1. Medicare.gov, "COBRA coverage" (2026)
2. Centers for Medicare & Medicaid Services, "Medicare & You 2027" (2027)
3. Centers for Medicare & Medicaid Services, "How Medicare Works with Other Insurance" (2026-02)
4. Medicare.gov, "When does Medicare coverage start?" (2026)
5. Centers for Medicare & Medicaid Services, "Employer Partners" (2026-09-16)
6. Centers for Medicare & Medicaid Services, "CMS-L564: Request for Employment Information" (2026)
7. Medicare.gov, "Special Enrollment Periods" (2026)
8. Medicare.gov, "When can I sign up for Medicare?" (2026)
9. Medicare.gov, "Working past 65" (2026)
10. North Carolina Department of Insurance, "Contact Seniors' Health Insurance Information Program (SHIIP)" (2026)
11. Centers for Medicare & Medicaid Services, "5 things you need to know about signing up for Medicare" (2026-03-10)