Quick answer: If you have to buy Part A (you don’t qualify for premium-free coverage) and don’t sign up when you’re first eligible, your premium can go up 10% — and you’ll pay that higher amount for twice the number of years you delayed.
This penalty only applies if you’re buying Part A. If you qualify for premium-free Part A, there’s no penalty for enrolling later, though delaying Part B enrollment has its own separate penalty to watch out for.
How the Penalty Is Calculated
For every full 12-month period you were eligible to buy Part A but didn’t enroll, your premium increases by 10%. You pay that higher premium for twice the number of years you could have had Part A but went without it.
A Worked Example
Say you were eligible to buy Part A for 2 years before you actually enrolled. Your premium would increase by 10%, and you’d pay that higher rate for 4 years (twice the 2 years you delayed) — then it would drop back to the standard premium.
Who This Actually Affects
Since most people get premium-free Part A automatically, this penalty mainly affects a smaller group: people who didn’t work (or whose spouse didn’t work) long enough to qualify for premium-free coverage, and who delay buying Part A after becoming eligible.
How to Avoid It
Sign up during your Initial Enrollment Period — the 7-month window that starts 3 months before the month you turn 65, includes your birthday month, and extends 3 months after. If you missed that window, enrolling during the General Enrollment Period (January 1 to March 31 each year) is your next opportunity, though the penalty clock is based on your delay, not when you eventually enroll.
Frequently Asked Questions
Do I get penalized if I already have premium-free Part A?
No. The late enrollment penalty for Part A only applies to people who have to buy Part A. If you qualify for premium-free Part A, delaying enrollment doesn’t trigger this penalty.
Is this the same as the Part B late enrollment penalty?
No, they’re separate. The Part B penalty adds 10% per full 12-month period you delayed, and unlike the Part A penalty, it lasts for as long as you have Part B — not just twice the delay period.
Can I avoid the penalty if I had other health coverage?
Possibly. If you had coverage through your own or a spouse’s current employer, you may qualify for a Special Enrollment Period that lets you sign up later without a penalty — see our enrollment guide for details.
