US Medicare enrollment penalties

Medicare enrollment in the United States is limited to a seven‑month window surrounding an individual’s 65th birthday. Enrolling within three months before or after the birthday avoids a permanent penalty, while missing the window can add a 10 % annual surcharge to Part B premiums for each year the person could have been covered. A special enrollment period is available for retirees still employed, but only if they are covered by a qualifying group health plan; individual plans, ACA exchanges, and COBRA do not qualify. Railroad Retirement Board beneficiaries face the same Part B late‑enrollment penalty unless they have qualifying employer or retiree coverage.

Later reports highlighted additional enrollment hurdles. When a retiring spouse enrolls, the surviving spouse’s employer‑based coverage may end, creating a 60‑day gap that can be filled by COBRA or an ACA marketplace plan. Medicare Advantage plan changes that lose a major hospital also trigger a 63‑day Special Enrollment Period, during which beneficiaries can switch plans, add a standalone Part D prescription plan, or return to Original Medicare. During these SEPs, Medigap insurers must offer eligible policies—often Plan G—without medical underwriting.