Didn't sign up on time? Estimate your Part B and Part D penalties — both last as long as you have the coverage.
Medicare describes late-enrollment penalties as additions to monthly premiums. They are not simply a one-time fee. The rules differ between Part A, Part B and drug coverage, so use the rule for the coverage in question.
Employer coverage can affect when you need to enroll. Confirm the type of coverage and the applicable enrollment rules with Medicare and the employer benefits administrator. A calculator cannot establish whether your coverage qualifies you for a Special Enrollment Period.
Income-related premiums and late-enrollment penalties are different issues. Check both on the official notice rather than using an income-related amount as a substitute for the penalty calculation.
Keep your eligibility date, coverage history, employer documentation and notices together. Start with the official sign-up instructions, then use a calculator to explore the arithmetic. If the official determination differs, follow the instructions for review rather than changing dates to force a lower estimate.
| Item | What it means |
|---|---|
| Part B penalty | Enrollment history and applicable exceptions. |
| IRMAA | Income-related premium adjustment. |
| Special Enrollment Period | Eligibility must be checked against official rules. |
Official sources: Medicare.gov official reference · Medicare.gov official reference
Last reviewed: 2026-10-12 — the added explanation and linked sources only. Existing calculator outputs and earlier content require separate validation. Educational information; not individualized insurance, tax or medical advice.
Quick answer: Medicare's late-enrollment penalties are permanent surcharges for signing up late. Part B adds 10% for each full 12 months you delayed; Part D adds 1% of the national base premium ($38.99 in 2026) for every uncovered month. Both last as long as you keep the coverage, so enrolling during your Initial Enrollment Period — or a valid Special Enrollment Period — is what avoids them.
A 5-minute weekly email for Medicare & insurance agents: enrollment windows, penalty math, compliance updates, and the tools that matter. No spam, unsubscribe anytime.
Educational only — not advice. We never share your email.
A permanent penalty is the clearest reason a T65 prospect shouldn't wait. Our T65 Pipeline Tracker and Medicare Agent OS (Excel + Google Sheets) keep every turning-65 lead on schedule so nobody you're working misses their window.
See the agent toolkits for free →Both the Part B and Part D late enrollment penalties are permanent — you pay them for as long as you have that coverage.
10% of the standard Part B premium for each full 12-month period you were eligible but didn't enroll. 30 months late = two full years = a 20% penalty.
1% of the national base beneficiary premium ($38.99 in 2026) times the number of full months you went without creditable drug coverage, rounded to the nearest 10 cents.
Yes — enroll during your Initial Enrollment Period, or keep creditable coverage (such as employer coverage) and enroll within the allowed window when it ends. See the Enrollment Period Finder.