Enrollment

Working Past 65 in Washington: Delaying Medicare Part B Without Penalties

If you are still working at 65 and have group health coverage from your own or your spouse's current job at an employer with 20 or more employees, you can delay Medicare Part B without a penalty and sign up later during an 8-month Special Enrollment Period. COBRA, retiree coverage and Marketplace plans don't count, and Washington's PEBB retiree coverage requires Parts A and B.

By the Benefits Life Editorial Team, licensed insurance agents · Reviewed November 9, 2026

The basic rule

You can delay Medicare Part B without a late enrollment penalty if you have group health coverage through your own or your spouse's current employment, and that employer has 20 or more employees. When you leave the job or lose the coverage, whichever happens first, you get an 8-month Special Enrollment Period to sign up for Part B.

The rule sounds simple, but the details matter. If you get them wrong, you can owe a Part B late enrollment penalty of 10% of the standard premium for each full 12-month period you could have had Part B but didn't, and you pay it for as long as you have Part B. See Medicare late enrollment penalties in Washington.

The big traps Washington workers fall into

Trap 1: COBRA doesn't count

COBRA continuation coverage from a former employer is not coverage based on current employment. Once you stop working, even if you keep paying for COBRA, your 8-month Special Enrollment Period counts from the month after your job or group coverage ends, not from when COBRA ends.

If you wait until COBRA runs out to sign up for Part B, you can miss your window and owe a penalty. Medicare.gov's advice is not to wait for COBRA to end before signing up.

Trap 2: Retiree health plans don't count

A former employer's retiree health plan doesn't let you delay Part B. You (or your spouse) must still be actively working for the employer whose plan covers you. Medicare.gov also warns that retiree coverage may not pay for your care if you don't have both Part A and Part B.

Washington PEBB retirees: the Health Care Authority requires anyone in PEBB retiree coverage who is eligible for Medicare to enroll and stay enrolled in Part A and Part B. See PEBB Medicare retirees and, for school employees, SEBB and Medicare.

Trap 3: Employers with fewer than 20 employees

If your or your spouse's employer has fewer than 20 employees, Medicare usually pays first at 65 and the employer plan pays second. In that case, plan to enroll in both Part A and Part B at 65, even if you keep the employer plan, because the employer plan may pay only what Medicare doesn't. Check with the plan's benefits administrator.

Many small Washington businesses fall into this group, such as family-owned restaurants, small clinics, nonprofits and startups. See Working at a small employer and Medicare.

Trap 4: HSA contributions and Medicare don't mix

If you have a Health Savings Account with a high-deductible health plan and want to keep contributing, you can't be enrolled in any part of Medicare, including Part A with no premium.

There's a second catch: when you sign up for Part A after 65, Part A coverage can start up to 6 months before the month you apply (but not before the month you turned 65). HSA contributions made during those months can become excess contributions with tax consequences.

Practical rule: to keep contributing past 65, don't start Social Security benefits (that enrolls you in Part A automatically) and don't sign up for Medicare. Medicare.gov says you and your employer should stop HSA contributions 6 months before you retire. See HSAs and Medicare at 65, and ask a tax professional about your own situation.

Should you enroll in Part A only?

For many Washington workers past 65, yes. Most people get Part A with no premium after 40 quarters of Medicare-taxed work. Part A can work alongside your employer plan, sometimes paying toward costs the employer plan leaves to you during a hospital stay (the 2026 Part A deductible is $1,736 per benefit period). Ask your benefits administrator how the plan works with Medicare.

The exception is the HSA situation above. If you're contributing to an HSA, hold off on Part A until you're ready to stop contributing.

The 8-month Special Enrollment Period

When your employment or your group coverage ends, whichever comes first, you have 8 months to sign up for Part B without a penalty. The period starts the month after the job or coverage ends.

When you lose employer coverage you also have other windows:

Medicare Advantage or a Part D drug plan: a separate Special Enrollment Period, generally the 2 full months after the month your employer coverage ends. To avoid a Part D penalty, keep creditable drug coverage or join a plan within that window.
Medigap: your federal 6-month Medigap open enrollment period starts the first month you are 65 or older and have Part B. If you delayed Part B because you were working, it starts when your Part B starts, not at 65.

Washington note: once you have a Medigap policy, Washington lets you switch at any time to another Medigap plan B through N (or from Plan A to another Plan A) without a health questionnaire (Office of the Insurance Commissioner; RCW 48.66.045). That right doesn't help you buy your first policy, so your open enrollment period still matters. See Medigap in Washington.

Form CMS-L564: proof of employer coverage

To sign up for Part B during your Special Enrollment Period, you send Social Security Form CMS-40B (the Part B application) with Form CMS-L564 ("Request for Employment Information"), which your employer completes to show you had group coverage based on current employment. Social Security also lets you do this online.

Plan ahead: ask HR for the form before you leave the job. Some employers are slow, and you don't want to chase paperwork while the 8 months run.

Common Washington scenarios

Tech worker still working at 65

You're 65 and still working at a large Puget Sound employer with group coverage. You can delay Part B. Take Part A only if you're not contributing to an HSA. When you retire, use the 8-month Special Enrollment Period and submit Form CMS-L564.

Large employer or supplier

Active employment with group coverage at an employer with 20 or more employees lets you delay. If you work for a smaller supplier or contractor, confirm the employer's size before you decide. When you retire, the Special Enrollment Period applies, but retiree coverage doesn't let you keep delaying.

Self-employed Washington consultant

Coverage you buy yourself on the individual market or through Washington Healthplanfinder isn't group coverage from current employment, so it doesn't let you delay Part B. Sign up during your Initial Enrollment Period at 65 to avoid a penalty.

State PEBB employee still working past 65

Active PEBB employees can delay Part B, because active state employment is current-employment coverage. When you retire, you must enroll in Parts A and B to keep PEBB retiree coverage, and HCA has strict deadlines. See PEBB rules.

Where to get help

The decisions around delaying Medicare depend on your employer and have lasting consequences. Help is available:

1-800-MEDICARE (1-800-633-4227, TTY 1-877-486-2048), the federal Medicare helpline, and Medicare.gov
Social Security (1-800-772-1213), for signing up and Form CMS-L564 questions
Your employer's HR or benefits administrator, for the employer's size and how its plan works with Medicare
A licensed insurance agent with Benefits Life, at (206) SENIORS (206-736-4677), TTY 711, at no cost to you, or an independent licensed insurance agent near you. When you're ready, you can also see plans in your ZIP code.

Sources

Frequently asked questions

Can I delay Medicare Part B if I'm still working at 65?

Yes, if you have group health coverage through your own or your spouse's current employment and that employer has 20 or more employees. When the job or the coverage ends, whichever happens first, you get an 8-month Special Enrollment Period to sign up for Part B without a late enrollment penalty.

Is COBRA creditable coverage for delaying Medicare?

No. COBRA doesn't extend your time to sign up for Part B. Your 8-month Special Enrollment Period starts when your job or your group coverage ends, not when COBRA ends. If you wait for COBRA to run out, you can miss the window and owe a Part B late enrollment penalty for as long as you have Part B.

Should I enroll in Part A at 65 if I'm still working?

Many people do, because most people get Part A with no premium after 40 quarters of Medicare-taxed work. The exception is a Health Savings Account: once you have any part of Medicare, you can no longer contribute to an HSA.

What is Form CMS-L564?

It is the Request for Employment Information form. Your employer fills it out to show you had group health coverage based on current employment, and you send it with your Part B application (Form CMS-40B) during your Special Enrollment Period. Ask HR for it before you leave the job.

Can Washington PEBB retirees delay Part B?

No. Retiree coverage isn't coverage from current employment, so it doesn't let you delay Part B without a penalty. The Health Care Authority also requires anyone in PEBB retiree coverage who is eligible for Medicare to enroll and stay enrolled in Part A and Part B.

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