QUICK ANSWER: If you worked past 65 with health coverage from your (or your spouse's) current employer, you get a Special Enrollment Period (SEP): you can sign up for Medicare Part B any time while you're still covered, and for 8 months after the employment or the coverage ends — whichever comes first. Enroll before your employer coverage ends to avoid a gap. COBRA and retiree coverage do not count as current employer coverage and do not extend this window.

More Southern Californians than ever are working past 65. If you delayed Medicare because you had good coverage through work, the transition when you finally retire has its own rules — different from turning 65 — and the deadlines are unforgiving if you miss them. Here's how it works, in plain English.

First: did you delay Medicare the right way?

If you (or your spouse) kept working past 65 for an employer with 20 or more employees, and you had group health coverage from that current employment, you could delay Part B without penalty. If that's you, you're in good shape — this guide is your roadmap out.

If your employer had fewer than 20 employees, Medicare generally should have become your primary coverage at 65. If you're in that situation and didn't enroll, talk to Social Security and your benefits administrator promptly — the rules differ, and our working past 65 in California guide covers the details.

Your Special Enrollment Period, explained

When current employment or the group coverage tied to it ends, you have an 8-month Special Enrollment Period to enroll in Part B (and premium Part A if applicable) without a late-enrollment penalty. The clock starts the month after employment or coverage ends — whichever comes first.

Three cautions that catch people:

Step by step: your transition timeline

2–3 months before your last day: start the paperwork

Enrolling while still covered is the cleanest path — no coverage gap. Apply for Part A and Part B through Social Security (ssa.gov, phone, or office). You'll need form CMS-L564 (employer verification of coverage) along with your request — ask HR to complete it. Pick a Part B start date that lines up with the day after your employer coverage ends.

Same window: decide your coverage approach

Once Part A and B are set, you'll choose between the two main paths — a Medicare Advantage plan, or Original Medicare paired with a Medigap policy and Part D drug plan. We compare them in Medicare Advantage vs. Medicare Supplement. Note for Californians: when you first enroll in Part B, you have a 6-month Medigap open enrollment window in which insurers can't decline you or charge more for health history — that window is valuable, use it deliberately.

Your last month of work: confirm the handoff

Verify your Part B effective date, enroll in your chosen plan (Medicare Advantage or Medigap + Part D — you have 2 months after group coverage ends for Advantage/Part D via SEP, but don't cut it close), and keep proof of your prior creditable drug coverage.

After retirement: watch the mail

Cards and plan confirmations should arrive before your start date. If your spouse was on your employer plan and is 65 or older, they need their own plan of action too — Medicare is individual; there's no family coverage.

What this costs (so there are no surprises)

In retirement you'll pay the standard Part B premium (higher-income households pay an income-adjusted amount, based on your tax return from two years prior — a retirement income drop can be appealed with form SSA-44). Your total costs then depend on the path you choose. Our Medicare costs explained guide breaks down the 2026 numbers.

Common transition mistakes

More in Common Medicare mistakes. If you're approaching 65 rather than retiring later, start with our Turning 65 step-by-step guide and the Turning 65 in Southern California overview.

Frequently asked questions

I'm retiring at 68 and have had employer coverage since 65. Do I owe a penalty?
Generally no — coverage from current employment (20+ employees) lets you delay Part B penalty-free, as long as you enroll during your 8-month SEP after that employment or coverage ends.
Does COBRA count as employer coverage for Medicare?
No. COBRA is not considered coverage based on current employment. Your 8-month Part B SEP runs from when employment ends, regardless of COBRA.
Can I get a Medigap plan when I retire after 65?
Yes. Your 6-month Medigap open enrollment period in California starts when you're 65+ and first enrolled in Part B — for many people who worked past 65, that's at retirement. During that window, insurers can't deny coverage or charge more due to health history.
What form do I need from my employer?
Form CMS-L564 (Request for Employment Information), completed by your employer, documents that you had group coverage — it's how Social Security confirms you qualify for the SEP without penalty.
Where can I get free help in Southern California?
Contact Medicare.gov or 1-800-MEDICARE, get free unbiased counseling from California's Health Insurance Counseling & Advocacy Program (HICAP) — California's State Health Insurance Assistance Program (SHIP) — at 1-800-434-0222, or work with an independent licensed insurance agent at no cost to you.

Sources & further reading

Last reviewed: July 2026. Medicare details can change annually — confirm current dates and amounts at Medicare.gov. Educational information only, not individualized advice.