IRMAA stands for income-related monthly adjustment amount. It's an extra charge added to your Medicare Part B premium, and to your Part D drug plan premium if you have one, when your income is above a set limit. Social Security makes the decision using information from the IRS.
Most people pay about 25% of what Part B really costs. People who owe IRMAA pay 35%, 50%, 65%, 80% or 85%, depending on their tier (POMS HI 01101.031). Three things decide your tier: your income figure (called MAGI), which tax year Social Security looks at, and your tax filing status. Here is how each one works.
1. Your income figure: MAGI
For IRMAA, modified adjusted gross income (MAGI) is two numbers from your federal tax return added together (POMS HI 01101.010; Form SSA-44):
- your adjusted gross income from line 11 of Form 1040, plus
- your tax-exempt interest from line 2a of Form 1040.
Yes, tax-exempt interest counts here, even though you don't pay income tax on it. That surprises a lot of people.
The federal regulation (20 CFR 418.1010) lists a few more items: interest from U.S. savings bonds used for higher-education tuition and fees, foreign earned income, and income from Guam, American Samoa, the Northern Mariana Islands or Puerto Rico. If none of those apply to you, your MAGI is simply line 11 plus line 2a.
Example: Your AGI on line 11 is $134,000 and line 2a shows $4,000 of tax-exempt interest. Your MAGI is $138,000. As a single filer in 2026, that puts you above the $137,000 line. That $4,000 of interest moves you up a whole tier, from $284.10 to $405.80 a month for Part B.
2. Which year: the 2-year lookback
Social Security uses the most recent tax information the IRS can provide. Generally, that's the return from two years before the premium year, and never more than three years before. So 2026 premiums are generally based on your 2024 tax return (POMS HI 01101.010).
If the IRS doesn't have your return from two years back, it sends the one from three years back (2023 for 2026). Social Security corrects the decision once the two-year-old data comes in (POMS HI 01101.030). Your IRMAA letter tells you which tax year was used.
If Social Security used a 3-year-old return
Say they used 2023, but you've already filed your 2024 return, or you didn't need to file one. You can ask them to use 2024 instead. This is its own kind of request, separate from a life-changing event. Bring a signed copy of the filed return, and if you filed electronically, print it and sign it. The change applies only to that premium year (POMS HI 01120.055).
The lookback is why IRMAA so often hits people right after they retire. Your premium in 2026 reflects your income in 2024, which might have been your last full year of paychecks.
See if an SSA-44 could lower your IRMAA. Start the free IRMAA check →
3. Your filing status picks the table
Social Security uses the filing status on that same tax return. There are three tables:
- Individual: single, head of household, qualifying surviving spouse, and married filing separately if you lived apart from your spouse the whole year.
- Married filing jointly: each limit is double the individual one, except the top tier, which starts at $750,000 instead of $500,000.
- Married filing separately, lived with your spouse at any point that year: only two tiers above $109,000, and the first one is already the second-highest charge.
The starting point (threshold) rises with inflation each year. Here are the recent ones (POMS HI 01101.010):
| Premium year | Married filing jointly | All other filing statuses |
|---|---|---|
| 2023 | $194,000 | $97,000 |
| 2024 | $206,000 | $103,000 |
| 2025 | $212,000 | $106,000 |
| 2026 | $218,000 | $109,000 |
4. Find your tier
Match your MAGI and filing status to a row. These are the official 2026 amounts. The married-filing-separately table is on our 2026 IRMAA brackets page.
| If your 2024 MAGI was | Part B premium per month | Part D add-on per month |
|---|---|---|
| $109,000 or less | $202.90 standard premium, no IRMAA | $0 (just your plan premium) |
| above $109,000 up to $137,000 | $284.10 includes $81.20 IRMAA | $14.50 + your plan premium |
| above $137,000 up to $171,000 | $405.80 includes $202.90 IRMAA | $37.50 + your plan premium |
| above $171,000 up to $205,000 | $527.50 includes $324.60 IRMAA | $60.40 + your plan premium |
| above $205,000 and less than $500,000 | $649.20 includes $446.30 IRMAA | $83.30 + your plan premium |
| $500,000 or more | $689.90 includes $487.00 IRMAA | $91.00 + your plan premium |
| If your 2024 MAGI was | Part B premium per month | Part D add-on per month |
|---|---|---|
| $218,000 or less | $202.90 standard premium, no IRMAA | $0 (just your plan premium) |
| above $218,000 up to $274,000 | $284.10 includes $81.20 IRMAA | $14.50 + your plan premium |
| above $274,000 up to $342,000 | $405.80 includes $202.90 IRMAA | $37.50 + your plan premium |
| above $342,000 up to $410,000 | $527.50 includes $324.60 IRMAA | $60.40 + your plan premium |
| above $410,000 and less than $750,000 | $649.20 includes $446.30 IRMAA | $83.30 + your plan premium |
| $750,000 or more | $689.90 includes $487.00 IRMAA | $91.00 + your plan premium |
The tiers are cliffs, not a slope
There is no gradual phase-in. Go even $1 over a limit and you pay the full charge for the next tier. A single filer with 2026 MAGI of $109,000 pays the standard $202.90. At $109,001, it's $284.10 for Part B plus $14.50 for Part D. That's $95.70 a month, or $1,148.40 a year, for one extra dollar of income.
Watch the exact wording at the edges. Most tiers run “up to” their top number, so $137,000 exactly is still in the $284.10 tier. But the row “above $205,000 and less than $500,000” stops just short, so a MAGI of exactly $500,000 lands in the top tier.
5. How the Part B and Part D charges add up
- Part B: the IRMAA is added to the standard premium. In 2026, a single filer with MAGI above $137,000 up to $171,000 pays $202.90 + $202.90 = $405.80 a month.
- Part D: the IRMAA is added on top of whatever your drug plan charges. It's based on a national base premium, not on your own plan's price. Social Security takes it out of your monthly Social Security payment, no matter how you pay the plan itself.
- Only what you have: if you have only Part B, or only drug coverage, you pay IRMAA only on that one.
- Late-enrollment penalty: a Part B late penalty is figured on the standard premium only, not on the IRMAA (POMS HI 01101.031).
A worked example, start to finish
You're single. Your 2024 return shows AGI of $147,000 and $3,000 of tax-exempt interest, so your MAGI is $150,000. That falls in the 2026 row “above $137,000 up to $171,000.” Your Part B premium is $405.80 a month: $202.90 standard plus $202.90 IRMAA. If you have a drug plan, you also pay $37.50 a month on top of the plan's premium.
Now say you retired in early 2026 and expect your 2026 MAGI to be about $95,000. That's under $109,000, so with the newer year you'd pay just the standard $202.90 and no Part D add-on. The difference is $240.40 a month ($202.90 + $37.50), or $2,884.80 a year.
Retirement counts as a life-changing event, so you don't have to wait two years for the lower premium. You can ask Social Security to use your 2026 estimate now with Form SSA-44. See using SSA-44 after you retire.
What can change the number
- A qualifying life-changing event lowered your income: file SSA-44. See the step-by-step SSA-44 instructions.
- They used a 3-year-old return: give them the 2-year-old one, as explained above.
- You filed an amended return, or the IRS figure is wrong: these follow their own steps. See what to do when you get an IRMAA letter.
- Married filing separately, but you lived apart all year: call Social Security at 1-800-772-1213 and ask them to use the individual table.
Want to see your own numbers? The free IRMAA and SSA-44 check shows your current tier, your likely new tier and the yearly difference.