Can You Have Medicare and Employer Insurance at the Same Time?

Having both is allowed — but they coordinate

Turning 65 while you (or your spouse) are still working does not force you off your job-based plan. Medicare and an employer group health plan can run side by side, and the two coordinate through rules Medicare calls "coordination of benefits."

Under these rules, one plan is the "primary payer" and pays your covered claims first, up to its limits. The other is the "secondary payer" and may pick up some of what's left, such as a deductible or coinsurance. The secondary payer does not always cover the full remainder, so you can still owe out-of-pocket costs.

The single most important factor in this setup is the size of the employer. That number decides who pays first and shapes nearly every other decision below.

Who pays first depends on employer size

Medicare uses a head-count threshold to decide which coverage is primary when you have job-based insurance based on current employment.

• 20 or more employees: The employer group health plan generally pays first, and Medicare pays second.
• Fewer than 20 employees: Medicare generally pays first, and the employer plan pays second.
• Medicare due to disability (under 65): If coverage is from current employment, the group plan generally pays first when the employer has 100 or more employees.
• Retiree coverage (no current employment): Medicare usually pays first, because retiree plans are not based on a current job.

Should you delay Part B while still working?

Part B carries a monthly premium — $202.90 in 2026 for most people — so many workers with solid employer coverage choose to delay it. Whether that's wise depends on your employer's size and how good the job-based plan is.

If your employer has 20 or more employees and the plan pays first, you can often safely delay Part B and avoid paying the premium until you stop working. If your employer has fewer than 20 employees, Medicare typically pays first, which usually means you should enroll in Part B on time so you are not left with large gaps.

Because the job is current employment, you generally qualify for a Special Enrollment Period (SEP). You can sign up for Part B while the group coverage and the current employment continue, or during the 8-month window that begins the month after that employment or coverage ends — whichever comes first. Enrolling within that window means no Part B late penalty.

Always confirm with your employer's benefits administrator how the plan works with Medicare before delaying. Some plans expect you to take Medicare at 65 and pay little if you don't.

Part A, HSAs, and prescription drug coverage

Most people qualify for premium-free Part A after 40 quarters (10 years) of Medicare-taxed work. Because it usually costs nothing, many people enroll in Part A at 65 even while keeping employer coverage. (If you don't have enough work history, Part A can cost $311/month with 30–39 quarters or $565/month with fewer than 30 quarters in 2026 — a reason some delay it.)

There's a major exception: Health Savings Accounts. Once you're enrolled in any part of Medicare, including premium-free Part A, you can no longer contribute to an HSA. If you want to keep contributing, you may need to delay Part A as well as Part B. Note that Part A coverage can be backdated up to 6 months when you eventually enroll, so plan to stop HSA contributions about 6 months before your Medicare start date to avoid an IRS tax penalty.

For prescriptions, you can delay Part D without a penalty as long as your employer drug coverage is "creditable" — meaning it meets Medicare's minimum standards. Your plan must tell you each year whether it is creditable. You avoid the Part D late penalty as long as you don't go more than 63 days without creditable drug coverage.

Penalties and 2026 costs to keep in mind

Delaying Medicare the wrong way can be expensive and, in some cases, permanent. Knowing the penalty math helps you decide.

• Part B late penalty: 10% added to your premium for each full 12-month period you could have had Part B but didn't — and it usually lasts for life. A valid SEP from current employment prevents this.
• Part D late penalty: 1% of the national base premium ($38.99 in 2026) times the number of full months you went without creditable coverage, added to your drug premium.
• Standard 2026 cost markers: Part B deductible $283/year, then you typically pay 20% coinsurance; Part A hospital deductible $1,736 per benefit period; Part D out-of-pocket cap $2,100/year.
• Higher-income surcharge (IRMAA): If your 2024 income was above $109,000 (single) or $218,000 (joint), your Part B premium can range up to $689.90/month and a Part D surcharge of $14.50–$91.00/month may apply — worth weighing if you're deciding whether to enroll while still earning.