An employer with 20 or more employees cannot force you to drop the company health plan and take Medicare when you turn 65. Federal law requires those employers to offer you the same coverage, on the same terms, as younger coworkers. If your employer has fewer than 20 employees, no one can physically enroll you in Medicare either, but the coordination rules flip in a way that usually makes enrolling the only sensible choice.
What Large Employers Cannot Do
If your employer had 20 or more employees on each working day in at least 20 calendar weeks during the current or prior year, the group health plan is the primary payer and Medicare is secondary. That order comes from the Medicare Secondary Payer statute, which also bars those employers from factoring your Medicare eligibility into your benefits at all.1Office of the Law Revision Counsel. 42 USC 1395y – Exclusions from Coverage and Medicare as Secondary Payer
In practice, that means your employer cannot:
- Drop you from the group plan because you became Medicare-eligible.
- Offer you a skinnier plan, charge you a higher premium, or carve out benefits because you turned 65.
- Treat a spouse age 65 or older differently from a younger spouse on the same plan.1Office of the Law Revision Counsel. 42 USC 1395y – Exclusions from Coverage and Medicare as Secondary Payer
The Age Discrimination in Employment Act reinforces the same idea: employers can let Medicare pick up certain services as secondary, but the combined coverage cannot leave an older worker worse off than a similarly situated younger one.2U.S. Equal Employment Opportunity Commission. EEOC Informal Discussion Letter
No Financial Incentives to Switch
Federal regulations specifically ban employers from offering financial sweeteners to push Medicare-eligible workers off the group plan. Your employer cannot offer you cash, a stipend, or an alternative benefit package (such as standalone drug coverage) to entice you to drop group coverage and rely on Medicare instead.3eCFR. 42 CFR 411.103 – Prohibition Against Financial and Other Incentives If HR proposes a Health Reimbursement Arrangement or cash payment contingent on you leaving the group plan for Medicare, that is exactly what the rule targets.
What Your Employer Can Reasonably Ask
The protection covers your right to stay on the group plan. It does not stop your employer from asking you to sign up for premium-free Medicare Part A alongside your group coverage. Medicare itself suggests checking with your employer about Part A when you turn 65.4Medicare.gov. Working Past 65 Because Part A has no premium for most people, enrolling in it while keeping the group plan adds hospital coverage at no cost, and many employer plans expect this so Medicare can pay secondary on hospital claims. That is not the same as being pushed off the plan.
If Your Employer Has Fewer Than 20 Employees
Small employers operate under a different framework. The Medicare Secondary Payer protections above do not apply, and Medicare becomes the primary payer for employees eligible based on age. The group plan pays second.5Centers for Medicare and Medicaid Services. MSP Employer Size for GHP Arrangements Part 1
A small employer still cannot enroll you in Medicare. Enrollment is always your decision. But if you skip it, the practical consequences can be severe. Because the group plan is only secondary, it expects Medicare to pay first. Without Medicare, no primary payer picks up its share, and the group plan may refuse to cover costs it considers Medicare’s responsibility.6Medicare.gov. How Medicare Works with Other Insurance You could end up with bills neither insurer pays. If you work for a company with fewer than 20 employees, enrolling in Part A and Part B at 65 is almost always the right call, even if you keep the employer plan as secondary coverage.
Multi-Employer and Union Plans
Multi-employer plans (common with union jobs and Taft-Hartley trusts) have a twist on the counting rule. If at least one contributing employer has 20 or more employees, the MSP rules apply to everyone in the plan, including workers whose own employer is small.5Centers for Medicare and Medicaid Services. MSP Employer Size for GHP Arrangements Part 1 The plan can elect a small-employer exception for workers whose own employer has fewer than 20 employees, which would make Medicare primary for those specific individuals.1Office of the Law Revision Counsel. 42 USC 1395y – Exclusions from Coverage and Medicare as Secondary Payer If you are approaching 65 in a multi-employer plan, ask the plan administrator whether that election has been made. The answer decides whether you need to sign up for Part B to avoid a coverage gap.
COBRA and Retiree Coverage Are Not Active Employment
One boundary trips people up repeatedly. COBRA continuation coverage and retiree health plans are not treated as coverage based on current employment, and the protections above go with the active job, not with the insurance card.
For retirees 65 or older, Medicare pays first and the retiree plan pays second no matter how large the former employer is. Retiree coverage may not pay anything during a period when you were eligible for Medicare but did not enroll.7Medicare.gov. Who Pays First
COBRA carries an extra sting. Medicare does not count COBRA as group health plan coverage for purposes of the Special Enrollment Period.8Medicare.gov. When Does Medicare Coverage Start If you leave a job at 65, elect COBRA, and assume you can sign up for Part B whenever COBRA ends, the eight-month Special Enrollment Period actually started when active employment ended. Miss that window and you face a coverage gap plus a permanent late enrollment penalty.
The Cost of Guessing Wrong: Late Enrollment Penalties
If you delay Medicare because you have coverage through your own or your spouse’s current employer, you qualify for a Special Enrollment Period that gives you eight months after the employment or group coverage ends (whichever comes first) to sign up for Part B without a penalty.8Medicare.gov. When Does Medicare Coverage Start COBRA, retiree plans, and individual market coverage do not qualify.9Centers for Medicare and Medicaid Services. Original Medicare Part A and B Eligibility and Enrollment
Miss that window without qualifying employer coverage and the Part B penalty is 10% added to your monthly premium for each full 12-month period you could have enrolled but didn’t. The surcharge is permanent; you pay it for as long as you have Part B.10Medicare.gov. Avoid Late Enrollment Penalties The standard Part B premium for 2026 is $202.90 per month.11Centers for Medicare and Medicaid Services. 12Centers for Medicare and Medicaid Services. Employer Services
Keep copies of your plan documents, any communications from HR about your age or Medicare eligibility, and any notice comparing your benefits to those offered younger employees. Those records are what turn a suspicion into a claim.