Medicare and Employer Coverage

Medicare and Employer Coverage

If you or your spouse is still working when you turn 65, you may be able to keep employer health insurance and delay Medicare Part B. The decision depends mainly on whether the coverage comes from current employment and how many people work for that employer. Those details determine which coverage pays first and whether delaying Part B can lead to out-of-pocket bills or a late-enrollment penalty.

For people eligible for Medicare because of age, an employer group health plan from an employer with 20 or more employees generally pays first. Medicare pays second. With fewer than 20 employees, Medicare generally pays first, even if you remain covered by the employer plan. These are Medicare Secondary Payer rules, explained by the Centers for Medicare & Medicaid Services.

Do not assume that a plan is safe to keep just because it has a familiar name or covers you well today. Ask the benefits administrator whether coverage is based on current employment, whether the plan pays primary or secondary to Medicare, and what enrollment timing the plan requires. This guide explains the rules that most often affect people turning 65, including Health Savings Accounts, COBRA, retiree plans, and prescription drug coverage.

Do you have to take Medicare at 65 if you are working?

Not always. Medicare eligibility and Medicare enrollment are different things. Most people become eligible for Medicare at 65, but active employer coverage can allow some people to postpone Part B. Your coverage can come through your own job or a working spouse's job. Coverage through a former employer, a retiree plan, COBRA, or a Marketplace plan follows different rules.

Medicare Part A helps pay for inpatient hospital care. Many people qualify for premium-free Part A based on work history and enroll at 65 even while keeping job-based coverage. Part B covers outpatient care, physician services, preventive services, and other medical care. Part B has a monthly premium, which is why many workers consider delaying it. Review the current 2026 Medicare Part B premium before deciding whether the cost savings outweigh the value of adding Medicare.

Before you delay Part B, confirm all of these points with your employer's benefits team:

• The insurance is a group health plan based on current employment.
• The employer has enough employees for the plan to pay before Medicare.
• The plan will continue to cover you as expected after you turn 65.
• You understand how deductibles, provider networks, and prescription benefits work alongside Medicare.

If you are approaching Medicare eligibility, our guide to enrolling in Medicare explains the enrollment periods and the forms you may need when job-based coverage ends.

Employer size decides who pays first

For Medicare eligibility based on age, the usual dividing line is 20 employees. If your employer, or your spouse's employer, has 20 or more employees and offers group health coverage based on current work, that group plan is generally primary. Medicare is secondary. You can generally wait on Part B and use a Special Enrollment Period later.

If the employer has fewer than 20 employees, Medicare is generally primary. The employer plan may pay only after Medicare's share. If you do not enroll in Part B, the group plan may pay little or nothing toward services Part B would have covered. That can leave you responsible for a large portion of a doctor, outpatient, or diagnostic bill.

Ask the benefits administrator to explain the plan's Medicare coordination rules in writing. In particular, ask how the employer counts employees, whether your plan has any Medicare enrollment requirement, and how claims are processed after you become eligible. The Medicare coordination of benefits guide provides additional examples of when Medicare pays first or second.

Different rules can apply when Medicare eligibility is based on disability or end-stage renal disease. For instance, a 100-employee threshold is often used for disability-related coordination, and end-stage renal disease has a 30-month coordination period. If either situation applies, speak with Medicare or your benefits administrator rather than relying on the age-65 rules in this article.

Your Special Enrollment Period when work or coverage ends

When your employment ends or your group health coverage based on current employment ends, you generally have an eight-month Special Enrollment Period to enroll in Part B without a late penalty. The clock starts the month after the employment ends or the group coverage ends, whichever comes first. You do not have to wait for COBRA to end, and waiting can create a coverage gap.

Medicare explains the rules and application steps on its Special Enrollment Period page. In many cases, you will submit Form CMS-40B to enroll in Part B and Form CMS-L564, completed by the employer, to show that you had qualifying group coverage.

Do not confuse this with the General Enrollment Period. If you miss your Special Enrollment Period, you may need to wait for the General Enrollment Period and could face a gap before Part B begins. You may also owe a Part B late-enrollment penalty for as long as you have Part B. See our explanation of the Medicare late enrollment penalty for how the penalty is calculated and when exceptions may apply.

Start planning several months before retirement or a loss of coverage. Compare your employer plan with Original Medicare, Medicare Supplement insurance, and Medicare Advantage options while you still have time to choose. Our Medicare when you retire guide can help you organize that transition.

Two traps: HSAs, COBRA, and retiree coverage

Health Savings Accounts

Once you enroll in any part of Medicare, you cannot contribute to a Health Savings Account, or HSA. This includes premium-free Part A. If you want to keep making HSA contributions through your employer, you may need to delay both Part A and Part B. The timing matters because when some people enroll in Medicare after 65, premium-free Part A can be retroactive for up to six months, though not before the month they became eligible. That retroactive coverage can affect HSA contribution eligibility.

The Internal Revenue Service explains Medicare and HSA contribution rules in IRS Publication 969. Coordinate the final HSA contribution with your benefits team or tax professional. Read our detailed Medicare and HSA guide before enrolling in any part of Medicare.

COBRA and retiree coverage

COBRA and retiree coverage usually do not count as group health coverage based on current employment for the Part B Special Enrollment Period. You may be able to elect COBRA after leaving a job, but that choice does not usually extend the eight-month Part B enrollment window. Retiree health coverage can also change how claims are paid once you are eligible for Medicare.

Prescription drug coverage

Part D has its own late-enrollment rules. If you keep employer drug coverage, ask each year whether it is creditable coverage, meaning it is expected to pay at least as much as standard Medicare Part D coverage. Save the employer's creditable coverage notice. You may need it to show that you can enroll in Part D later without a penalty. When you are ready to evaluate options, use our Medicare plan comparison guide to focus on your medications, doctors, and expected costs.

Choosing coverage after employer insurance ends

When job-based coverage ends, you can enroll in Original Medicare, which includes Part A and Part B, and then decide whether to add Part D prescription drug coverage and a Medicare Supplement policy. You can also consider a Medicare Advantage plan, which combines Part A and Part B benefits through a private plan and usually includes drug coverage.

The right option depends on your doctors, prescriptions, travel habits, budget, and willingness to use a provider network. A Medicare Supplement policy can help with Original Medicare cost sharing, while Medicare Advantage plans often use network and prior authorization rules. Review Medicare Advantage versus Medicare Supplement coverage for a plain-language comparison before you choose.

Medicare timing is personal, but the rules are not something to guess at. Keep records of your active employer coverage, creditable drug coverage notices, and any forms submitted to Social Security. A short conversation with your benefits administrator before retiring can prevent an avoidable enrollment problem later.