Leaving Employer Coverage? Start Medicare on Time (2026–2027)
Bottom Line
Arrange Part B through Social Security before employer coverage ends if eligible, and separately confirm your private policies' start dates. COBRA doesn't extend the employment-based Part B deadline, and drug-plan enrollment has a separate, shorter window.
To avoid a gap when employer insurance ends, confirm your last covered day, arrange Part B through Social Security, and separately schedule any Medigap, Part D, or Medicare Advantage coverage. Apply before employer coverage ends if eligible; do not treat Part B’s eight-month enrollment window as a reason to wait.
If you are also reviewing life insurance for your family or estate, comparing guaranteed universal life rates is a separate budgeting decision, unrelated to Medicare eligibility or enrollment.
Confirm exactly what ends and when
To plan Medicare around work and retirement, get written dates from your benefits administrator; your last workday and last insured day may differ.
Ask for:
- The date employment ends.
- The last day of active employee medical coverage and prescription coverage.
- Whether coverage will continue through a working spouse, COBRA, or a retiree plan.
- What happens to a spouse or dependents when you leave the plan.
When planning Medicare coverage for retirement after 65, establish when replacement coverage is needed, then compare coverage choices separately from completing enrollment.
If coverage ends midmonth, ask Social Security about starting Medicare on the first of that month and your employer about overlap. Part B start dates follow monthly enrollment rules.
Use the right Part B enrollment window
If you delayed Part B and have had qualifying group coverage through your own or a spouse’s current employment since turning 65, you can generally enroll while that coverage continues or during the eight months after employment or coverage ends, whichever happens first.
If you are still in your seven-month Initial Enrollment Period around 65, its rules apply instead. The employment-based window does not apply to eligibility based on End-Stage Renal Disease.
Make your Medicare decisions before relying on COBRA: COBRA does not extend the Part B deadline. Retiree coverage is also different from coverage based on current employment, and its eventual termination does not create this Part B enrollment opportunity.
If you missed the eight-month deadline, ask SSA whether another Special Enrollment Period applies. Otherwise, General Enrollment runs January 1–March 31, with coverage the next month and possible late penalties.
Prepare and submit your Medicare application
The documents to gather before Medicare enrollment include your termination notice, employment and coverage dates, Medicare number if already enrolled, and prescription plan’s creditable coverage notice. Keep application copies and submission confirmations.
Use the application that matches your situation:
- Need both Part A and Part B: Apply through Social Security’s Medicare enrollment service. An employment-based Special Enrollment Period also requires CMS-L564.
- Already have Part A: Apply for Part B online or submit CMS-40B with CMS-L564, the Request for Employment Information, for the employment-based enrollment period. Have the employer complete its section.
If the employer cannot complete CMS-L564, SSA accepts alternative evidence, such as pay stubs showing health insurance deductions or explanations of benefits. Follow SSA’s instructions for completing the form without the employer’s signature.
Part B generally begins the month after enrollment. While still working with qualifying coverage, or within the first full month after employer coverage ends, you can request a start date up to three months later. Verify the approved date.
Check HSA timing before applying
Premium-free Part A can start retroactively up to six months before you apply, but not before eligibility. HSA contributions cannot be made for Medicare-covered months. If applying six months or more after 65, generally stop your and your employer’s contributions at least six months before applying for Medicare or Social Security.
Choose your medical and prescription coverage
Original Medicare consists of Part A, hospital insurance, and Part B, medical insurance. Medigap, also called Medicare Supplement Insurance, helps pay certain remaining costs. Medicare Advantage is another way to receive Medicare benefits.
| Choice | What you arrange | Main buying questions |
|---|---|---|
| Original Medicare with Medigap and standalone Part D | Parts A and B, a separate Medigap policy, and a drug plan | What are the combined premiums and remaining costs? Do your providers accept Medicare? |
| Medicare Advantage with drug coverage | Parts A and B plus a Medicare Advantage plan that includes Part D | Are your doctors and hospitals in network? What are the authorization rules, copays, and annual medical spending limit? |
| Medicare with employer retiree benefits | Medicare enrollment plus any required employer elections | What does the retiree plan pay, which drugs are covered, and what happens to family benefits? |
Original Medicare has no annual limit on your share of covered medical bills. Medigap helps pay those costs. Medicare Advantage plans have an annual limit for covered Part A and Part B services, but networks and costs vary. You still pay the Part B premium with either route; Medigap does not supplement Medicare Advantage. Retiree benefits depend on the employer’s plan.
Match every plan’s effective date
If you already have Parts A and B, focus on these remaining coverage decisions. Part B enrollment is separate from enrolling in an individual private plan.
Medicare Advantage requires Parts A and B; standalone Part D requires Part A or Part B. You must meet other eligibility requirements, including living in the service area. Coverage generally starts the first of the month after the plan receives your request.
Leaving employer or union coverage, including COBRA, gives you a plan enrollment opportunity lasting two full months after the month coverage ends. That is separate from Part B’s eight-month window.
Arrange drug coverage without a gap. After your initial drug enrollment period, going 63 consecutive days or longer without Part D or other creditable prescription coverage can trigger a Part D late penalty. Creditable means the coverage is expected to pay at least as much, on average, as Medicare drug coverage.
Example: employer coverage ends October 31, 2026
This hypothetical schedule assumes eligibility for the employment-based enrollment period:
- Start preparing during August or September. Submit the Medicare application in advance and request November 1 for Part B.
- Arrange the chosen Medicare Advantage or Part D plan before October ends, using the applicable enrollment period and requesting November 1. Employer-coverage enrollment rules permit prospective enrollment.
- If choosing Medigap, request November 1 separately and obtain confirmation from the insurer. Its effective date is not set automatically by your Part B application.
Annual enrollment, October 15–December 7, normally produces a January 1 start the following year. For November 2026 coverage, use the appropriate 2026 enrollment route. Review 2027 coverage separately using that year’s official plan documents.
Protect your Medigap buying rights
Your federal six-month Medigap Open Enrollment Period starts the first month you are at least 65 and enrolled in Part B. During this window, insurers cannot deny a policy they sell or charge more because of your health. Retirement does not restart a window that already ran. Annual Medicare open enrollment does not generally guarantee Medigap without medical underwriting. State laws may provide additional protections.
If Part B started earlier, ask whether losing your employer coverage creates a guaranteed issue right. One federal protection applies if you have Original Medicare and your secondary employer plan is ending. Apply within 63 days of the latest applicable date: coverage termination, the date on the termination notice, or the date on a claim denial first revealing termination. Eligible policies are limited; retain your notices.
Check public employee and postal retiree benefits
Before coordinating public employee retiree benefits with Medicare, identify your system: state or local employer coverage, federal FEHB, or postal PSHB. Ask about Medicare requirements, spouse coverage, and whether dropping benefits affects future eligibility. Joining outside drug coverage can cause loss of employer retiree benefits for you or family members.
FEHB itself does not require Part B enrollment. Its drug coverage is creditable, so check the existing benefits before adding standalone Part D.
Postal retirees have different Part B requirements
When coordinating PSHB benefits with Medicare, check each person’s requirements. Certain Medicare-eligible postal annuitants and family members must enroll in Part B to retain PSHB.
Exceptions include employees who were 64 or older on January 1, 2025, and annuitants who retired on or before January 1, 2025, and are not already enrolled in Part B. Additional exceptions and family-member rules apply. Verify the relevant exception before declining Part B.
Compare coverage and confirm your start dates
Compare plans using your ZIP code, effective date, doctors, hospitals, prescriptions, dosages, and pharmacies. Evaluate premiums plus expected medical and drug costs, and verify provider participation directly. For Medigap, request written quotes for equivalent benefits and the same start date from multiple insurers.
Before employer coverage ends, compare its final covered date with the confirmed start dates for Medicare and each policy you chose. Resolve missing approvals or date mismatches with Social Security, the insurer, or your benefits administrator. Use that confirmed schedule and cost comparison to make your coverage decision.