Medicare Part B Penalty Calculator

The simple math behind the Part B late penalty — and what it could cost you over time.

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Quick answer

To calculate your Medicare Part B penalty, add 10% to the standard premium for each full 12-month period you delayed Part B without qualifying coverage. In 2026, a one-year delay adds about $20.29 to the $202.90 monthly premium, for life, per Medicare.gov.

Wondering what a late Part B sign-up will cost? Here is how to calculate the penalty.

How do you calculate the Part B penalty?

The Medicare Part B late enrollment penalty adds 10% to your premium for each full 12-month period you were eligible for Part B but did not enroll, without qualifying coverage. To calculate it, count the full years you delayed, multiply by 10%, and apply that percentage to the standard premium. For example, a 2-year delay is a 20% penalty: 20% of the $202.90 standard 2026 premium is about $40.58 extra per month. Because the penalty is a percentage of the standard premium, it can grow as premiums rise each year, and it generally lasts for life.

What does the penalty cost over time?

The Part B penalty looks small monthly but compounds over decades. A 20% penalty of roughly $40.58 a month is about $487 a year — and if you live 20 more years with Medicare, that exceeds $9,700 in extra premiums, before accounting for premium increases that raise the penalty further. That is why enrolling on time, or keeping qualifying employer coverage and using a Special Enrollment Period, matters so much. To confirm whether your coverage lets you delay penalty-free, call 1-800-MEDIGAP (1-800-633-4427) before your enrollment window closes.

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Frequently asked questions

How do I calculate the Medicare Part B penalty?+

Add 10% to the standard Part B premium for each full 12-month period you delayed enrollment without qualifying coverage. For 2026, a 2-year delay is a 20% penalty, adding about $40.58 to the $202.90 monthly premium. The penalty generally lasts for life.

Does the Part B penalty increase over time?+

Yes. The penalty is a percentage of the standard Part B premium, so as the premium rises each year, the dollar amount of your penalty rises too. A penalty set at 10% or 20% keeps applying to the current premium for as long as you have Part B.

How long do I pay the Part B penalty?+

The Medicare Part B late enrollment penalty generally lasts for as long as you have Part B, making it effectively permanent. This is why enrolling on time or maintaining qualifying coverage and using a Special Enrollment Period is so important.

Can I avoid the Part B penalty entirely?+

Yes. Enroll during your Initial Enrollment Period around age 65, or keep qualifying coverage like active employer insurance and enroll through a Special Enrollment Period when it ends. Call 1-800-MEDIGAP (1-800-633-4427) to confirm your coverage qualifies.

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