You can sign up for Medicare at 65 even if you're still employed, but the timing affects your coverage and your costs

If you're working past 65, you have a choice: sign up for Medicare when you turn 65, or wait. The right choice depends on whether your employer covers health insurance and how many employees work there. If your employer has 20 or more employees and offers health coverage, you can usually skip Medicare Part B (doctor and outpatient care) without penalty and keep your work insurance as primary. If your employer has fewer than 20 employees, or doesn't offer coverage, you should sign up for Medicare Part A (hospital insurance) and Part B at 65 to avoid a permanent penalty on Part B premiums.

The key date is the month you turn 65. You have a seven-month window to sign up without penalty — three months before, the month of, and three months after your birthday month. Missing this window costs you 10 percent more on Part B premiums for each year you delay, and that increase is permanent.

Key Takeaways

  • If your employer has 20 or more workers and offers health insurance, you can delay Medicare Part B while you work there without paying a penalty later.
  • If your employer has fewer than 20 workers, or offers no health coverage, sign up for Medicare Part A and Part B at 65 to avoid a permanent 10 percent annual premium increase.
  • You have seven months to sign up without penalty: three months before your 65th birthday, the month of your birthday, and three months after.
  • Part A (hospital insurance) has no monthly premium for most people, so there is no penalty for signing up early even if you delay Part B.
  • When you leave your job or your employer coverage ends, you have eight months to sign up for Part B without penalty, starting the month your coverage stops.

How employer coverage affects your Medicare timeline

Your employer's size and coverage matter because Medicare has a rule called creditable coverage. If your employer has 20 or more employees and offers health insurance, your work plan is considered creditable — meaning it counts as "real" coverage in Medicare's eyes. You can stay on your employer plan and skip Medicare Part B without penalty, even after 65.

When you eventually leave that job or the coverage ends, you get an eight-month window to sign up for Part B without penalty. This window starts the month your employer coverage stops, not the month you turn 65. So if you work until 68 and your coverage ends in June, you have until February of the following year to sign up for Part B without penalty.

If your employer has fewer than 20 employees, or offers no health plan at all, your work coverage does not count as creditable. You should sign up for Medicare Part A and Part B at 65. Waiting costs you: Part B premiums go up 10 percent for each 12-month period you delay after your initial enrollment window closes.

What happens if you miss the seven-month window

The seven-month enrollment window is three months before your birthday month, your birthday month itself, and three months after. If you turn 65 in March, your window runs from December through June. If you do not sign up during this time and you do not have creditable coverage from an employer with 20 or more workers, you will pay a penalty.

The Part B penalty is 10 percent of the standard premium for each full 12 months you were may be able to access but not signed up. If the standard premium is $175 a month and you delay two years, your premium becomes $192.50 a month — permanently. Even if you sign up later, that higher rate stays with you.

Part A (hospital insurance) has no monthly premium for most people, so there is no penalty for signing up late. However, if you delay Part A and later need hospital care, you could face a deductible. It is simpler to sign up for Part A at 65 even if you delay Part B.

Signing up while employed: the steps and timing

You can sign up for Medicare online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office. You will need your Social Security number, proof of citizenship or legal residency, and proof of age (usually your birth certificate). The process takes about 15 minutes online.

Start the process in the month before your 65th birthday so your coverage begins the month you turn 65. If you sign up in your birthday month, coverage typically starts the first of the following month. If you wait until after your birthday month, there may be a gap in coverage.

If you are keeping your employer coverage and delaying Part B, you still need to sign up for Part A. When you do sign up, tell Medicare that you have employer coverage. This protects you from the Part B penalty later, as long as your employer has 20 or more workers. Keep records of your employer coverage — the plan name, dates covered, and your employer's size — because you will need to show this when you sign up for Part B after you leave the job.

When to sign up if you're self-employed or have a small business

If you own a business or work for yourself, you do not have employer coverage that counts as creditable. Sign up for Medicare Part A and Part B at 65. Your business size does not matter — the creditable coverage rule applies only to employees of employers with 20 or more workers.

If you have a spouse who is employed by a company with 20 or more workers and you are covered under their plan, that coverage is creditable for you. You can delay Part B. But if you are self-employed or work for a small business, you need your own Medicare coverage.

Coordinating Medicare with your work health insurance

Once you sign up for Medicare, you need to decide which coverage is primary — the one that pays first. If you have both Medicare and employer coverage, the rules depend on your employer's size.

If your employer has 20 or more workers, your employer plan is primary and Medicare is secondary. Your employer plan pays first, and Medicare covers what it does not. If your employer has fewer than 20 workers, Medicare is primary and your employer plan is secondary. This matters because it changes what you pay and which claims go where.

Tell your employer's benefits office that you have signed up for Medicare. They need to know so they can coordinate benefits correctly. Some employers adjust your coverage or premiums once you are on Medicare, so check your plan documents or ask your HR department what changes when you enroll.

What to do when you leave your job

When you stop working or your employer coverage ends, you enter a new enrollment window. You have eight months starting from the month your coverage stops to sign up for any Medicare parts you have not yet enrolled in, without penalty.

If you delayed Part B because you had creditable coverage, this is when you sign up for it. Do not wait — the eight-month window is your protection against the permanent penalty. After those eight months, the 10 percent annual increase applies if you were not signed up during your original seven-month window at 65.

You can sign up online, by phone, or at a Social Security office. Have your employer coverage end date ready, and be prepared to explain that you had creditable coverage. This documentation protects you from penalties.

Frequently Asked Questions

Can I stay on my employer plan after 65 instead of signing up for Medicare?

Yes, if your employer has 20 or more workers and offers health insurance. Your employer plan can be your primary coverage. You should still sign up for Medicare Part A at 65 because it has no premium and protects you if you need hospital care. When you leave the job, you have eight months to sign up for Part B without penalty.

What if I sign up for Medicare but want to keep my employer coverage too?

You can have both. If your employer has 20 or more workers, the employer plan is primary and Medicare is secondary. If your employer has fewer than 20 workers, Medicare is primary. Tell your employer's benefits office that you have Medicare so they can coordinate correctly. Some employers may adjust your coverage or premiums once you are enrolled in Medicare.

Do I pay a penalty if I sign up for Medicare Part A but not Part B?

No. Part A has no monthly premium for most people, so there is no penalty for signing up early or late. The 10 percent annual penalty applies only to Part B (doctor and outpatient care). If you have creditable employer coverage, you can delay Part B without penalty as long as you work there.

What counts as creditable coverage for Medicare purposes?

Creditable coverage is health insurance from an employer with 20 or more employees. It must cover hospital and doctor services. Coverage from a small business, self-employment, or a spouse's plan at a small employer does not count. Medicare will tell you whether your coverage qualifies when you sign up.

How do I prove I had creditable coverage when I sign up for Part B later?

Keep your employer plan documents, coverage end date, and a record of your employer's size. When you sign up for Part B after leaving the job, provide this information to Medicare. You can also ask your former employer's benefits office for a letter stating the coverage dates and that the plan was creditable. This protects you from penalties.