Still Working at 65? What You Must Do and What You Can Skip

The short version: insurance from a job where you or your spouse still works usually lets you wait on Part B (Medical Insurance) with no penalty. COBRA, retiree coverage, and VA care do not, even though they're real coverage. And if the employer has fewer than 20 employees, waiting can leave bills unpaid even while you're insured. The details, and the two forms you'll eventually need, are below.

Do I have to sign up for Medicare while I'm still working?

No law forces anyone to sign up. The real question is whether your current insurance lets you delay Part B without a late penalty later, and the answer depends on one thing: the coverage has to be a group health plan based on current employment, yours or your spouse's. If it is, you can wait until the work (or the coverage) ends, then sign up penalty-free. Source: Medicare.gov, "Working past 65," 2026.

Part A (Hospital Insurance) is its own decision. If you don't pay a premium for Part A, and most people don't, you can take it at 65 or any time later. One caution before you take even free Part A: if you're putting money into a Health Savings Account, there's a separate rule to check first, because Medicare.gov says you and your employer should stop HSA contributions 6 months before you retire or apply for Social Security to avoid a tax penalty. Source: Medicare.gov, "Working past 65," 2026.

Why does the size of the company matter?

Because it decides who pays your medical bills first. Medicare calls this "coordination of benefits," and the dividing line for people 65 and older with job-based coverage is 20 employees:

20 or more employees: the job's plan pays first and Medicare pays second. Your employer plan is carrying the load, so delaying Part B while the work continues is usually safe.
Fewer than 20 employees: Medicare pays first and the job's plan pays second. That means without Part A and Part B, there may be no "first payer" at all for much of the bill. Medicare.gov's advice here is direct: ask the employer whether you need to sign up at 65, because if you don't, your job-based insurance might not cover the costs of your care.

Source: CMS, "How Medicare Works with Other Insurance," Pub. 02179, February 2026, and Medicare.gov, "Working past 65," 2026.

One wrinkle: a small employer that's part of a multi-employer plan (common with unions and trade associations) can be treated like a large one if any employer in the group has 20 or more employees. The benefits office can tell you which side of the line the plan is on, and the person to ask is the plan's benefits administrator, not a salesperson. Source: CMS, Pub. 02179, February 2026.

What counts as job-based coverage, and what doesn't?

This is where people get burned, because plenty of things feel like employer coverage but don't protect your sign-up window. The test is active employment: someone has to still be working there.

COBRA does not count. Your 8-month sign-up window starts when the work stops, even if you take COBRA afterward. Medicare.gov says it plainly: don't wait until COBRA ends to sign up for Part B, because COBRA doesn't extend your limited time to sign up. Source: Medicare.gov, "Working past 65," 2026.
Retiree coverage does not count. Once you're retired, Medicare pays first and the retiree plan pays second. A retiree plan may also refuse to pay for periods when you were eligible for Medicare but hadn't signed up, so check with the benefits administrator before you lean on it. Source: CMS, Pub. 02179, February 2026.
VA health care does not protect the window either. VA care is real coverage inside VA facilities, but Medicare doesn't pay for care you get at a VA facility, and the VA itself encourages signing up for Medicare as soon as you can. Its own guidance says that if you delay Part B and need to sign up later, you'll pay a penalty that grows each year you wait. Source: VA.gov, "VA health care and other insurance," 2025, and CMS, Pub. 02179, February 2026.
TRICARE has its own rule. TRICARE For Life requires both Part A and Part B, so military retirees generally need to enroll rather than delay. Source: CMS, Pub. 02179, February 2026.

How does the 8-month window work when the job ends?

Once you (or your working spouse) stop working, or the job-based coverage ends, whichever happens first, an 8-month Special Enrollment Period opens. During it you can sign up for Part B (or add it to Part A) with no late penalty. The window is meant for people who've had job-based coverage from current employment ever since they first became eligible for Medicare, and the clock starts at the stop-work date even if you take COBRA. Source: Medicare.gov, "Working past 65," 2026, and Form CMS-L564, rev. March 2025.

Don't use all eight months if you can help it. Coverage starts the month after Social Security processes your application, so Medicare.gov suggests signing up about a month before your employer coverage ends to avoid a gap. And missing the window entirely is expensive: the Part B late penalty adds 10% of the standard premium ($202.90 a month in 2026) for each full 12-month period you could have signed up but didn't, and it usually lasts as long as you have Part B. The details are in our guide to when to sign up for Medicare. Source: Medicare.gov, "Avoid late enrollment penalties," 2026, and SSA FAQ, 2026.

One pleasant side effect of waiting correctly: your one-time 6-month Medigap (Medicare Supplement Insurance) open enrollment window starts the first month your Part B is active, with no health questions allowed. If a Medigap plan is on your list to consider, that's the moment, and our Plan G vs Plan N guide explains the two letters most people weigh. Source: Medicare.gov, "When can I buy a Medigap policy," 2026.

What forms do I need when I'm ready?

Two, and they travel together. CMS-40B is the actual application for Part B. CMS-L564 (called "Request for Employment Information") is the proof that you had job-based coverage, which is what earns you the penalty-free window. You fill out Section A of the L564, your employer (or your spouse's) fills out Section B, and you mail or fax both forms to your local Social Security office. You can find the office at SSA.gov/locator. Source: Form CMS-L564, rev. March 2025.

If the employer is out of business, unreachable, or just won't sign, you're not stuck. Social Security's own rules say that when the employer can't provide the evidence, you may submit other documents that show the employment and the coverage: pay stubs showing health insurance premium deductions, W-2s reflecting pre-tax medical contributions, health insurance cards with a policy effective date, explanations of benefits, premium receipts, or tax returns showing premiums paid. Source: SSA program manual (POMS HI 00805.295), 2024.

Quick answers to common questions

My insurance is through my spouse's job. Does that count?

Yes. Coverage from your spouse's current employment protects your sign-up window the same way your own would. The 8-month window then starts when your spouse stops working or the coverage ends, whichever comes first. Source: Medicare.gov, "Working past 65," 2026.

Can I just stay on COBRA until it runs out?

You can keep COBRA, but it won't hold your Part B window open. The 8 months run from when the work stopped, so an 18-month COBRA stretch can quietly carry you past the deadline and into penalty territory. If you're helping a parent sort this out, this is the trap to check first. Source: Medicare.gov, "Working past 65," 2026, and U.S. Department of Labor COBRA continuation coverage rules (18-month maximum after employment ends).

I have VA health care. Can I skip Part B?

You can, and some veterans do, but know the trade: Medicare won't pay at VA facilities, VA won't act as job-based coverage for the window, and the VA itself recommends signing up for Medicare as soon as you can. Delaying means a penalty if you ever want Part B later. Source: VA.gov, 2025.

Do I have to take Part A at 65 if I'm still working?

Not necessarily. If your Part A is premium-free you can take it at 65 or any time later, and many people take it while delaying Part B. The main reason to pause is the HSA contribution rule mentioned above, which is worth checking before you enroll in anything. Source: Medicare.gov, "Working past 65," 2026.

Every situation here turns on facts only you (or your benefits office) know: who's still working, how big the employer is, where the coverage really comes from. The free, official sources below can look at your specific case, and none of them will try to sell you anything.