IRMAA is a surcharge on your Medicare Part B and Part D premiums that depends on your income from two years earlier. For 2026, Social Security reads your 2024 tax return (or 2023 if no 2024 data is available), and if your modified adjusted gross income (MAGI) is above $109,000 for a single filer or $218,000 for a joint return, you pay more. It is a cliff, not a slope, so a single dollar can cost over a thousand dollars a year. If your income has dropped since then because of a qualifying event, you can ask Social Security to use a more recent year with Form SSA-44.
How the two-year lookback works
The premium you pay in a given year is set from the tax return filed for the year two years before it. The law says Social Security uses the individual’s income “for the individual’s last taxable year beginning in the second calendar year preceding the year involved.” In practice:
| Premium year | Tax return used |
|---|---|
| 2026 | 2024 |
| 2027 | 2025 |
| 2028 | 2026 |
If the IRS has no data for the lookback year in electronic form, the law lets Social Security use the year before that. That is the “or 2023 if 2024 is not available” wording in the 2026 table.
Two things follow. A decision you make this December shows up in the premium year two years later, after it is too late to change. And the premium you pay today reflects a life you may no longer be living, for example if you were still working when that return was filed.
The table of tiers lives on the 2026 IRMAA brackets page. This article is about the rules behind it.
What MAGI means for IRMAA
IRMAA uses its own definition of MAGI. It starts with adjusted gross income, the number at the bottom of the first page of your Form 1040, and adds tax-exempt interest. The statute also computes AGI without regard to sections 135, 911, 931 and 933 of the tax code, which puts back savings bond interest used for education and certain foreign and territory income that was excluded.
What this means in practice:
- Municipal bond interest counts even though it is not in your AGI.
- A Roth conversion counts in full, because the converted amount is taxable income.
- Required minimum distributions count.
- Qualified charitable distributions do not, because they never enter AGI.
- Roth IRA withdrawals do not.
On a joint return, each spouse’s IRMAA is measured against the return’s MAGI. If both of you are on Medicare and the joint MAGI is over the line, you each pay the surcharge. For other MAGI definitions, such as the Roth IRA or net investment income tax versions, see what MAGI means.
The cliff: one dollar over means the full surcharge
Every tier has a threshold. At exactly $109,000 of MAGI a single filer pays no surcharge. At $109,001 the filer is in the first tier.
| Single filer, premium year 2026 | MAGI $109,000 | MAGI $109,001 |
|---|---|---|
| Part B surcharge per month | $0.00 | $81.20 |
| Part D surcharge per month | $0.00 | $14.50 |
| Surcharges per year | $0.00 | $1,148.40 |
Nothing is prorated. The $1,148.40 comes from $81.20 for Part B plus $14.50 for Part D, times twelve. The standard Part B premium of $202.90 is unchanged. The filer’s Part B total becomes $284.10 a month.
The Part D amount is on top of whatever your drug plan charges. Social Security’s table reads ”$14.50 + Plan premium” for the first tier.
Married couples filing separately face a harsher scale, and only if they lived together at some point in the year. Check the 2026 brackets page before assuming the single or joint rows apply.
Life-changing events and the SSA-44
You cannot appeal the lookback just because you dislike it. Social Security will, however, set it aside for a short list of events that cut your income. The list is exclusive, which means events outside it do not count no matter how much they hurt:
- Death of a spouse
- Marriage
- Divorce or annulment
- Work reduction
- Work stoppage
- Loss of income-producing property
- Loss of employer pension
- Receipt of a settlement payment from a current or former employer
For these, the question is whether your MAGI fell significantly. Social Security defines that as a reduction that decreases or eliminates IRMAA for a specific tax year. If it did, you can ask Social Security to make a new initial determination using a more recent tax year, on the basis of your statement, made under penalty of perjury, that the event caused the drop. You use Form SSA-44, which is optional, or you can contact Social Security another way.
Some details that catch people out:
- It is not an appeal. A request based on a life-changing event is a new initial determination. A formal appeal is a separate request for reconsideration and is due within 60 days of receiving the notice, which Social Security counts as 5 days after the date on it. When you describe a qualifying event, they treat it as a new determination and do not take an appeal unless you insist.
- Timing. The new determination is effective in January of the year you ask, or your first month of Part B if later. A qualifying event in October to December of the prior year can reach back to January of that year if you ask by March 31.
- A spouse needs their own request. A report applies only to the person making it.
- Estimates are accepted. If you have not yet filed the more recent year’s return, you give an estimate for that year and may also give one for the next.
- Amended returns. Social Security can use an amended return, with an IRS receipt letter or transcript, in place of the return on file, even if it raises your premium.
Worked example: retiring versus converting
A single filer had $150,000 of MAGI on the 2024 return and stopped working in 2025. Their 2026 premium is set from the 2024 return, which puts them in Tier 2 with $2,884.80 a year of surcharges. They estimate 2026 MAGI at $60,000, which is the standard tier with no surcharge. Work stoppage is on the list, so the SSA-44 can remove the $2,884.80.
A second single filer had $100,000 of MAGI, then converted $30,000 to a Roth IRA in 2024. MAGI became $130,000, which is Tier 1 and $1,148.40 of extra surcharge in 2026. Social Security’s list of one-time increases that do not qualify includes an IRA conversion, along with property sale gains, lottery and casino winnings, and cashing bonds. Their income “dropped” in 2025, but no listed event caused it, so the SSA-44 does not apply. The only formal route is the reconsideration request, within its 60 days, and it needs a reason that fits the rules.
Common triggers
- Roth conversions. The most common surprise, because the conversion is voluntary and the bill arrives two years later. Plan the size of each conversion against the tier above your expected MAGI. See Roth conversion and IRMAA.
- Selling a home or investments. Taxable gain raises MAGI in the year of sale. It is a one-time spike, which Social Security does not treat as a life-changing event. The part of a home sale gain you exclude is not in AGI.
- Required minimum distributions. RMDs count in full, and they start at a fixed age whether or not you need the money. A qualified charitable distribution keeps the donated amount out of MAGI.
- Tax-exempt interest. Easy to overlook, because it never appears on the tax you owe.
- Capital gain distributions from funds. They arrive late in the year and are hard to predict.
What to do now
- Find which return is being used. 2027 premiums will be based on your 2025 return and 2028 premiums on your 2026 return. Year-end moves in 2026 matter for 2028.
- Check your notice. If your income fell because of one of the eight events, file the SSA-44 with proof of the event, such as a marriage certificate, death certificate, retirement letter or pension statement.
- If the return itself was wrong, amend it and send Social Security the IRS receipt letter or transcript.
- Plan the next two years. Model your own MAGI against the tiers with the IRMAA calculator and, for the effect of an appeal, the SSA-44 planner.
CMS publishes each year’s tier table in the autumn before the year starts. This article uses only the 2026 table that is in force; the next one will appear on the brackets page once CMS releases it. This is general information about how the rules work, not advice for your situation.