Updated July 28, 2026. Quick answer: Normally your premium is set by the return from two years earlier. But the lookback is not always two years: where Treasury lacks adequate data as of 15 October before the premium year, the statute directs the use of the third preceding year instead. That single exception explains most cases where a beneficiary is certain SSA used the wrong income.
Which return applies
| Situation | Return used |
|---|---|
| Ordinary case | Two years before the premium year |
| Treasury lacks adequate data by 15 October | Three years before |
This is why the “SSA used the wrong year” complaint is so often not an error at all. A late-filed or extended return frequently means the two-year-prior data is not available in time, and the statute then requires the older year. If your income was much higher three years ago, that is the number you are being charged on — correctly.
What to do if the older year was used
The fix is usually a new initial determination rather than an appeal, once the more recent return is available. SSA’s own guidance treats that as the normal route, and it is faster than the appeal process people reach for first.
The planning consequence
Any income event you create today lands on a premium two years out — sometimes three. So the year you do a large conversion or realise a large gain is not the year you feel it, and by the time the surcharge appears the decision is long past changing. And you cannot appeal it away afterwards.
No dollar thresholds appear here. Most IRMAA bracket boundaries are CPI-indexed and change annually, and the top boundary is on a different schedule from the rest. Take the current year’s thresholds from CMS or the Social Security Administration directly.
Run your own numbers. ESPP disposition calculator — compare a qualifying and disqualifying sale.
Sources
42 U.S.C. §1395r(i) (Social Security Act §1839(i)), including §1395r(i)(4) (the year used and the modified adjusted gross income definition) and §1395r(i)(5) (inflation adjustment and its exclusions); 20 C.F.R. §418.1205 and §418.1210 (life-changing events and the exclusivity of that list); SSA Program Operations Manual System HI 01120.005 and HI 01140.005. All read July 2026.
This states what the cited authority says. It is not tax advice, and retirement-plan design turns on facts about your business and your other entities that no page can see. Every dollar limit referenced here is indexed and changes annually.