Part B late enrollment penalty calculator
Signed up for Part B late, or about to? Enter two dates and see the penalty Medicare adds to every Part B bill, and what waiting another year would cost.
| Sign up in | Penalty | Extra a month | Over 20 years* |
|---|---|---|---|
| Jan–Mar 2027 | 10% | $20.29 | $4,869.60 |
| Jan–Mar 2028 | 20% | $40.58 | $9,739.20 |
| Jan–Mar 2029 | 30% | $60.87 | $14,608.80 |
* At the 2026 premium. The premium usually rises each year, and the penalty rises with it. Social Security makes the official calculation. Months you were covered by a current job never count; months without any job coverage after your first sign-up window do. Waiting one more year adds another 10%.
Before you accept a penalty: if your employer, plan or a broker told you that you didn't need Part B yet, you may qualify for a special window with no penalty. The Part B Late Enrollment Kit covers it in Bonus #3, step by step.
How the penalty works
The penalty is 10% of the standard Part B premium for each full 12 months you could have had Part B but didn't. It's added to your premium every month for as long as you have Part B. In 2026 the standard premium is $202.90 a month.
| Full years late | Penalty | Extra a month | Extra a year |
|---|---|---|---|
| 1 | 10% | $20.29 | $243.48 |
| 2 | 20% | $40.58 | $486.96 |
| 3 | 30% | $60.87 | $730.44 |
| 5 | 50% | $101.45 | $1,217.40 |
At the 2026 premium of $202.90. The premium usually goes up each year, and the penalty with it.
What counts, and what doesn't
- Doesn't count: months you were covered by a group health plan from your own or your spouse's current job.
- Counts: months after your first sign-up window when you had no job coverage, including months on COBRA, retiree coverage, or individual insurance.
- Counting ends at the end of the enrollment period you sign up in. For the General Enrollment Period, that's March 31.
Worked past 65? You may owe nothing
Already late? Try these first
- Recount your 8 months. Count from the month after the job or its coverage ended, not from the end of COBRA. If your spouse's job still covers you, your clock hasn't started.
- Wrong information from an employer, plan or broker? You may get a special window with no penalty. Apply with Form CMS-10797 and proof of what you were told.
- Wrong information from Social Security or another federal employee? Ask for equitable relief in writing.
- None of these? Sign up in the very next General Enrollment Period, January 1 to March 31. Every year you wait adds another 10%.
- Limited income? Ask your state Medicaid office about the Medicare Savings Programs, which can pay your Part B premium, penalty included.
Includes Bonus #3, "If You Missed the 8 Months": the special windows, equitable relief, and how to appeal a penalty you think is wrong.
Filled-in examples of Forms CMS-40B and CMS-L564, plus a plan for when your old employer is slow, gone, or won't sign.
- Filled CMS-40B example
- Filled CMS-L564 example for your employer
- If your employer won't sign or is gone
- 8-month deadline worksheet
- Plus 3 free bonuses, including the Letter to Your Employer's HR
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Retiring after 65? Get both kits for $69 instead of $88. Save $19 with the bundle
The official forms are free from ssa.gov and cms.gov. The kit is the help filling them in and proving your case. See everything inside
Questions people ask
How is the Part B late penalty calculated?
It's 10% of the standard Part B premium for each full 12-month period you could have had Part B but didn't. Months you were covered by a group health plan from a current job don't count. Social Security counts to the end of the enrollment period in which you finally sign up.
How long does the Part B penalty last?
For as long as you have Part B, in most cases for life. It's recalculated from the standard premium each year, so it goes up when the premium goes up.
I worked past 65 with job coverage. Will I pay a penalty?
Not if you sign up within 8 months after the job or the coverage ends, whichever comes first. That's your Special Enrollment Period. COBRA and retiree coverage don't extend it.
Can the penalty be removed?
If an employer, plan or broker gave you wrong information about when to sign up, you may qualify for an exceptional-conditions Special Enrollment Period (Form CMS-10797) with no penalty. If a federal employee gave you wrong information, ask Social Security for equitable relief. If you think the penalty was counted wrong, ask for reconsideration within 60 days of the letter.
Is 11 months late a penalty?
No. Only full 12-month periods count. 23 months without Part B is one full period, so 10%.