Free tool
What would a late Part B penalty cost me?
The Part B late penalty is 10% for every full year you could have signed up and didn't, and you pay it for life. See what that adds up to in real dollars.
What this can't do: An estimate. If you had job-based coverage you may owe nothing at all.
Why this one hurts more than people expect
Most late fees are a one-off. This isn't. It attaches to your monthly premium and stays there for as long as you have Part B, which for most people means the rest of their life. Two years late is a 20% surcharge every month for twenty-odd years.
It also moves in steps, not smoothly. Eleven months late costs nothing. Twelve months late costs 10% forever. There is no partial credit for being nearly on time.
The good news is that the most common reason people are "late" isn't a penalty at all. Coverage from a current employer generally protects you, and there's a separate window for when that coverage ends. Still working at 65 walks through which situations qualify, and the 7 enrollment mistakes that cost real money covers the rest.
Nothing you type here leaves your device
This tool runs entirely inside your own browser. What you enter is never sent to us, never stored, and never shared. You can disconnect from the internet after the page loads and it will still work. That is deliberate: we tell people never to hand their Medicare number to a website, so this site had better not be one that asks.
Where these numbers come from
These are the 2026 amounts. CMS usually publishes the next year's figures in mid-November and SSA in October; after that, check the source links before relying on a result.
Free, official help with your own decision
This tool does arithmetic on published rules. For a decision about your own coverage, use the official sources. They're free and they don't sell anything.
- Medicare.gov The official government site to compare plans and check coverage yourself.
- SHIP: free local counseling Your State Health Insurance Assistance Program: free, unbiased Medicare help.