US Medicare Enrollment Rules Pose Lifetime Penalties, Including Railroad Beneficiaries

Medicare enrollment is limited to a seven‑month window surrounding a person's 65th birthday. Signing up within three months before or after the birthday avoids a permanent penalty; missing the window can add a 10 % annual surcharge to Part B premiums for each year the individual could have been covered. A special enrollment period is available for those who are still employed, but only if they are covered by a qualifying group health plan—generally a workplace plan with 20 or more employees. Individual plans, ACA exchanges, and COBRA continuation coverage do not qualify, meaning many retirees who mistakenly skip enrollment may face lifelong higher costs.

Railroad retirees have a parallel Medicare program administered with the Railroad Retirement Board. Eligibility includes railroad retirement beneficiaries aged 65 or older, individuals with end‑stage renal disease, disabled beneficiaries under 65, and those with ALS. Those already receiving railroad retirement or Social Security benefits are automatically enrolled in Medicare Parts A and B; others must contact the RRB before turning 65. The same Part B late‑enrollment penalty applies if they decline coverage without qualifying employer or retiree coverage.