How to use this calculator
- Pick the premium year. The penalty is recalculated each year from that year’s standard premium and base premium.
- Enter the months without Part B that count toward the penalty: from the end of your initial enrollment period until your Part B coverage started, leaving out any months you had group coverage from your or your spouse’s current job.
- Enter the months without drug coverage: full months after your initial enrollment period with no Part D and no other creditable drug coverage.
- Enter how many years you expect to pay to see a rough total. It assumes today’s premiums, which usually rise over time.
Your initial enrollment period is the 7 months around your 65th birthday: the 3 months before your birthday month, that month and the 3 months after.
How the Part B penalty works
If you don’t sign up for Part B when you’re first eligible, and you don’t qualify for a special enrollment period, your monthly premium may go up 10% for each full 12-month period you could have had Part B but didn’t. Only full 12-month periods count: a gap of 23 months adds 10%, and 24 months adds 20%.
The penalty is a percentage of the standard Part B premium ($202.90 a month in 2026), so each 10% adds $20.29 a month this year. It’s added on top of any IRMAA you pay, and you usually pay it for as long as you have Part B. Higher earners may also owe an income-related surcharge: see 2026 IRMAA brackets.
If you missed your initial enrollment period, you can sign up during the general enrollment period, January 1 to March 31 each year. Coverage starts the month after you sign up.
Most people get premium-free Part A. If you have to buy Part A and sign up late, a separate penalty applies: your Part A premium may go up 10%, for twice the number of years you could have had it but didn’t.
How the Part D penalty works
If you go 63 days or more in a row without Part D or other creditable drug coverage after your initial enrollment period ends, you may owe a Part D late enrollment penalty when you join a plan. Medicare calculates it as:
The national base beneficiary premium is $38.99 for 2026 ($36.78 in 2025). The penalty is added to your drug plan’s premium, whatever plan you choose, for as long as you have Part D coverage. Because the base premium can change each year, so can the penalty. To avoid a gap, follow our Medicare open enrollment checklist each fall.
Worked examples
- Part B, 29 months late: that’s two full 12-month periods, so the penalty is 20%. In 2026: 20% × $202.90 = $40.58 a month, or $486.96 a year, on top of the $202.90 premium.
- Part D, 14 months without drug coverage: 14% × $38.99 = $5.46, rounded to $5.50 a month, added to the plan premium.
- Part B, 11 months late: no full 12-month period has passed, so there’s no Part B penalty.
2026 penalty amounts at a glance
Part B late enrollment penalty by the number of full years you went without Part B:
| Years without Part B | Penalty | Extra per month (2026) | Extra per year | Your Part B premium |
|---|---|---|---|---|
| 1 | 10% | $20.29 | $243.48 | $223.19 |
| 2 | 20% | $40.58 | $486.96 | $243.48 |
| 3 | 30% | $60.87 | $730.44 | $263.77 |
| 4 | 40% | $81.16 | $973.92 | $284.06 |
| 5 | 50% | $101.45 | $1,217.40 | $304.35 |
| 10 | 100% | $202.90 | $2,434.80 | $405.80 |
Part D late enrollment penalty by the number of full months without creditable drug coverage:
| Months without drug coverage | Penalty | Extra per month (2026) | Extra per year |
|---|---|---|---|
| 3 | 3% of $38.99 | $1.20 | $14.40 |
| 6 | 6% of $38.99 | $2.30 | $27.60 |
| 12 | 12% of $38.99 | $4.70 | $56.40 |
| 18 | 18% of $38.99 | $7.00 | $84.00 |
| 24 | 24% of $38.99 | $9.40 | $112.80 |
| 36 | 36% of $38.99 | $14.00 | $168.00 |
| 48 | 48% of $38.99 | $18.70 | $224.40 |
| 60 | 60% of $38.99 | $23.40 | $280.80 |
When you won’t owe a penalty
- Job-based coverage: if you or your spouse are still working and covered by that employer’s group health plan, you can delay Part B. Sign up within 8 months after the job or the coverage ends, whichever happens first, to avoid the penalty.
- Creditable drug coverage: drug coverage from an employer, union, TRICARE, the VA or the Indian Health Service that’s expected to pay at least as much as standard Part D coverage. Plans send a yearly notice saying whether they’re creditable; keep it.
- Extra Help: if you qualify for Extra Help with drug costs, you don’t pay a Part D penalty.
- Disability: if you’re under 65 and pay a penalty, it ends when you turn 65 and get a new enrollment period.
COBRA and retiree coverage don’t count as coverage from current work for Part B, so ending COBRA doesn’t start a special enrollment period. Many people are surprised by this; plan your Part B start date before COBRA runs out.
How to challenge a penalty
Part D: your drug plan tells you about the penalty in writing. If you think it’s wrong, for example because you had creditable coverage, you can ask for a reconsideration, generally within 60 days of the date on the letter. Send proof, such as the creditable coverage notice from your former plan.
Part B: if you had job-based coverage and still received a penalty, contact Social Security with proof of that coverage, such as a form completed by your employer. Keep records of any coverage you had while you delayed enrolling.
Frequently asked questions
How much is the Medicare Part B late enrollment penalty?
How is the Part D late enrollment penalty calculated?
Do I pay the penalty for life?
Will I get a penalty if I had health insurance through work?
Does the penalty go up every year?
Sources
- Avoid late enrollment penalties — Medicare.gov
- 2026 Medicare Parts A & B premiums and deductibles — Centers for Medicare & Medicaid Services
- Medicare & You handbook — Centers for Medicare & Medicaid Services