By Christian BrinkleyLicensed NC Insurance Agent, NPN 22217190, NC Life & Health · Updated October 10, 2026 · 4 min read
Your Initial Enrollment Period runs seven months: the three months before your 65th birthday month, your birthday month, and the three months after. Miss it, and two things happen. First, you pay a late penalty on Part B, and possibly on Part D, and both penalties follow you for as long as you have Medicare. Second, you wait. You generally cannot sign up until the next General Enrollment Period, which runs January 1 to March 31 each year. There is one big exception, and it saves a lot of people: if you had health coverage through active employment, you may qualify for a Special Enrollment Period instead.
The Part B penalty: 10 percent per year, for life
Part B charges a late enrollment penalty of 10 percent of the standard premium for each full 12-month period you were eligible but did not sign up. The standard premium is $202.90 a month in 2026. Wait one full year and you add about $20.30 a month to your premium. Wait three years and that is about $60.90 a month extra.
It never goes away. It is not a fine you pay once. It is baked into your monthly premium for as long as you have Part B, which for most people means the rest of their life. A short delay of a month or two adds nothing, because the penalty only counts full 12-month periods, but a long delay compounds into real money.
The Part D penalty: 1 percent per month, for life
Drug coverage has its own penalty with different math. If you go 63 days or more without creditable drug coverage after you become eligible, Medicare adds 1 percent of the national base beneficiary premium to your monthly Part D premium for every month you went without. The base premium is $38.99 in 2026, so each month of delay adds about 39 cents.
Twelve months late adds about $4.70 a month to whatever your plan charges. Like the Part B penalty, it has no end date. And because the base premium changes each year, the dollar amount of your penalty can drift upward over time even though the percentage stays fixed.
When you can actually sign up
If you missed your Initial Enrollment Period and do not qualify for a Special Enrollment Period, your next chance is the General Enrollment Period, January 1 to March 31 each year. Since 2023, coverage starts the first day of the month after you enroll, so signing up in February means March 1 coverage. Before that change, everyone waited until July 1.
You also get a two-month Special Enrollment Period to join a Part D drug plan once you sign up during the General Enrollment Period. Use it. Going without drug coverage while you wait just grows the Part D penalty.
The exception: creditable employer coverage
This is the part that saves a lot of people. If you were covered by a group health plan through your own or your spouse's current employment, and the employer has 20 or more employees, you get an 8-month Special Enrollment Period when that coverage ends. Enroll during it and there is no penalty at all.
But two kinds of coverage do not count: COBRA and marketplace plans. People on COBRA often assume they are protected, and they are not. If your only coverage was COBRA, you owe the penalty and you wait for the General Enrollment Period like everyone else.
What to do right now
First, figure out whether you qualify for a Special Enrollment Period. If you or your spouse worked past 65 with group coverage from an employer with 20 or more employees, call Social Security and ask. If not, mark January 1 on your calendar and use the General Enrollment Period.
Second, do not skip Part D while you wait. A low-cost drug plan during the gap keeps the Part D penalty from growing. Third, keep every letter about past coverage. If Medicare questions whether your old coverage was creditable, the proof is on you.
Questions people ask me about this
Does the Part B late penalty ever go away?
No. It stays in your monthly premium for as long as you have Part B. The only way to avoid it is to enroll on time or qualify for a Special Enrollment Period.
What if I only missed it by a month or two?
The Part B penalty only applies per full 12-month period, so a short delay adds nothing. The Part D penalty counts month by month after a 63-day gap, so even a few months can add a small permanent amount.
Can I get Part A late without a penalty?
Most people get premium-free Part A based on their work history, and there is no late penalty for it. If you have to buy Part A because of limited work history, a separate penalty can apply.
Does COBRA count as creditable coverage for Medicare?
No. COBRA and marketplace plans do not qualify you for a Special Enrollment Period, and they do not protect you from the Part B penalty. Only group coverage from current employment counts.
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