Questions & answers · Health insurance
What is the Part D late enrollment penalty and how is it figured?
Health insuranceBuying a policyChecked Nov 6, 2026
From K.Actuary, founded by Sangmin Kwon, ASA · sources checked 2026-11-06 · Source: Medicare.gov · Your coverage options View original ↗
In short
- You may owe a penalty if you wait to join a drug plan.
- It is 1% of a base premium for each full month you went without.
- You usually pay it as long as you have Part D.
What this means
Medicare.gov says you may pay a Part D late enrollment penalty if you don't join a drug plan when you first get Medicare and then go 63 days or more without creditable drug coverage [1]. The penalty goes up the longer you wait. In most cases you pay it as long as you have Part D coverage, even if you switch plans [1].
The penalty is 1% times the national base beneficiary premium times the number of full, uncovered months you were eligible but did not join. The base premium is $38.99 in 2026. The amount is rounded to the nearest $.10 and added to your monthly premium [2]. The base premium may go up each year, so your penalty may also go up [2]. The sources do not say how to tell if your old drug coverage was creditable.
Your next step
Check the date you first could join a drug plan. Count the full months without drug coverage. Ask your drug plan for its notice of the penalty if you got one. The sources give no deadline.
Check it yourself
Your plan's notice shows the exact amount. If you think the penalty is wrong, the notice tells you how to ask for a review — "Don't know yet" the steps here.
Where this comes from (2)
[1] Medicare.gov · Your coverage options · checked 2026-11-06
You may pay a Part D late enrollment penalty if you don't join a Medicare drug plan when you first get Medicare and go 63 days or more without creditable drug coverage … The penalty goes up the longer you wait to join a plan … In most cases, you pay this monthly penalty for as long as you have Part D coverage, even if you switch plans
[2] Medicare.gov · How much does Medicare drug coverage cost? · checked 2026-11-06
Part D late enrollment penalty is calculated by multiplying 1% times the … ($38.99 in 2026) times the number of full, uncovered months you were eligible to join Medicare drug coverage but didn't … That amount is rounded to the nearest $.10 and added to your monthly premium … may go up each year
How we found this
We matched your question to 2 official sources, quoted the exact lines, and re-checked each quote against its source on 2026-11-06.
What we don’t know yet
Your own plan or notice may say something different. If your letter cites another rule, send it and we will look again.
Every answer is checked against the official rule it quotes.
Information only — not legal advice. Your plan, insurer or agency decides.
This answer quotes the official sources listed above, with the date we checked them. Your own policy, notice and state rules control. We are not your lawyer or your insurer. We don’t file, argue or negotiate claims for you — you send any letter or form yourself.
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