Part B Late Enrollment Penalty
The Part B late-enrollment penalty is permanent: 10% of the standard premium for every full 12 months you delay without creditable coverage — and it silently inflates every Medigap quote for life.
| Delay | Penalty | 2025 Basis ($185 standard) |
|---|---|---|
| 12 months late | +10% | ≈ $18.50/month forever |
| 24 months late | +20% | ≈ $37/month forever |
| 5 years late | +50% | ≈ $92.50/month forever |
How the penalty interacts with Medigap
Medigap supplements Part B costs, so a inflated Part B premium rides along invisibly in every plan comparison — the penalty never appears on the Medigap quote itself. Avoiding it is enrollment timing (see the IEP file); fixing it is nearly impossible.
The legitimate escapes
Active employer coverage (own or spouse’s, 20+ employee companies) earns a special enrollment period with no penalty — document it. COBRA and retiree plans do NOT count the same way; the rules and edge cases tie into GI rights when that coverage ends.
FAQ
Is the Part B penalty one-time or monthly?
Monthly, forever — 10% per full 12-month delay, added to every future premium.
Does Part D have a similar penalty?
Yes — 1% of the national base premium per uncovered month; see the FAQ library.
Related reading: All windows · IEP file · Medicare FAQs