Editorial note: Figures on this page reflect the 2026 Medicare program year and are cross-referenced against the official Centers for Medicare & Medicaid Services (CMS) publications. Always confirm current numbers before making enrollment decisions.
How employer coverage works with Medicare
If the employer has 20 or more employees, the group health plan generally pays first and Medicare pays second. Many people in this situation take premium-free Part A and delay Part B.
If the employer has fewer than 20 employees, Medicare generally pays first. In that case you usually need Part A and Part B when you are first eligible, or the employer plan may not pay for much of your care.
When to sign up for Part B
- If you delayed Part B because of current employer coverage, you can sign up during an 8-month Special Enrollment Period that starts when the job or the coverage ends, whichever comes first.
- COBRA and retiree coverage do not count as coverage based on current employment for this purpose.
- Ask your employer to complete the form that confirms your group coverage so Social Security can apply the Special Enrollment Period.
Avoiding late penalties
- Part B: the penalty can be 10% for each full 12-month period you could have had Part B but didn't, and it generally lasts as long as you have Part B.
- Part D: if you go 63 days or more without creditable drug coverage, a penalty can be added. Ask your employer each year whether its drug coverage is creditable.
- Contributing to a Health Savings Account: you generally need to stop contributions before Medicare coverage starts, since Part A can begin up to 6 months retroactively.
Medicare Disclaimer: We do not offer every plan available in your area. Any information we provide is limited to those plans we do offer in your area. Please contact Medicare.gov or 1-800-MEDICARE (TTY: 1-877-486-2048) to get information on all of your options. Medicare has neither reviewed nor endorsed this information.
Medicare has neither reviewed nor endorsed this information. For a complete list of plans in your area, call 1-800-MEDICARE (TTY: 1-877-486-2048).