Yes, you can have both Medicare and employer insurance at the same time, and many people do when they work past age 65. The key question is which one pays first — known as 'coordination of benefits.'
Which pays first depends on employer size:
If your employer has 20 or more employees: - Your employer plan pays FIRST (it's 'primary') - Medicare pays SECOND (it's 'secondary'), covering some costs the employer plan doesn't - You can often delay enrolling in Medicare Part B (and avoid its premium) while you have this coverage, then enroll penalty-free when you stop working
If your employer has fewer than 20 employees: - Medicare typically pays FIRST - The employer plan pays second - In this case, you usually should enroll in Medicare Part A and B when first eligible, because Medicare is your primary coverage
Key decisions: - Part A (hospital): Usually free if you've worked 40 quarters, so most people enroll even with employer coverage — there's rarely a downside. - Part B (medical): Has a monthly premium ($185 in 2025). Whether to delay it depends on your employer's size and coverage. Delaying when you have qualifying employer coverage avoids the premium AND avoids the late-enrollment penalty.
Important warning about HSAs: If you contribute to a Health Savings Account, you cannot contribute once you enroll in any part of Medicare. If you want to keep funding an HSA, you may need to delay Medicare enrollment entirely.
Because the rules are complex and mistakes can cause permanent penalties, confirm your specific situation with Medicare (1-800-MEDICARE) or your employer's benefits administrator.