The quick answer
Maybe not. If you have group health coverage based on current employment (yours or your spouse's) at an employer with 20 or more employees, you can usually delay Part B without a penalty. With a smaller employer, Medicare usually pays first, so you'll likely need Part B.
Why employer size matters
- 20+ employees: the employer plan generally pays first; Medicare pays second.
- Fewer than 20 employees: Medicare generally pays first. Without Part B, your employer plan might pay very little.
Always confirm with your employer's benefits administrator.
Coverage that doesn't count
COBRA, retiree coverage, and individual Marketplace plans are not coverage based on current employment. Relying on them may lead to a Part B late enrollment penalty.
If you have an HSA
You can't contribute to a Health Savings Account once you have any part of Medicare. If you enroll after 65, Part A can be backdated up to 6 months, so stop contributions in time. Ask your tax advisor.
When you retire
You'll generally have 8 months after your employment or coverage ends (whichever comes first) to sign up for Part B. You'll use Form CMS-40B and have your employer complete Form CMS-L564. See the retiring-after-65 guide.
This page is general educational information, not personal advice. Medicare rules, costs, and plan options change and depend on your situation. For official information, visit Medicare.gov or call 1-800-MEDICARE (1-800-633-4227; TTY 1-877-486-2048).