Is IRMAA calculated every year?
Yes, in two separate ways. Social Security sets your surcharge fresh for every premium year, working from the newest filing the IRS can hand over, generally two years old and never more than three, so 2026 premiums rest on 2024 MAGI. The income lines that trigger the surcharge also move annually with inflation: the first threshold sat above $106,000 single and $212,000 joint for 2025 and sits above $109,000 and $218,000 for 2026, while the top tier stays frozen at $500,000 and $750,000 until 2028. Because every year stands alone, an expensive tax year affects a single premium year; how long a surcharge runs before it drops off has its own page.
How does Social Security recalculate IRMAA each year?
Automatically. You file nothing and request nothing; "calculated" and "recalculated" describe the same machinery, one annual redetermination. Each fall SSA matches the newest IRS data against the coming year's tiers and mails the result: the annual notice arrives in November, ahead of the January change. A different letter, the Initial IRMAA Determination, can show up in any month, typically when someone first enrolls or when the IRS transmits updated figures.
Do the IRMAA brackets change every year too?
Yes, by statute. The law fixes a set of base thresholds and ties them to inflation: each year's tiers scale the base by CPI-U growth, measured over the 12 months that close in August, with the result rounded to the nearest $1,000 (42 U.S.C. §1395r(i)(5)). The exception is the top tier, held until 2028 at $500,000 for singles and $750,000 for joint filers. The movement is visible across just two years:
| Premium year | Return SSA reads | Tier 1 begins, single filer | Tier 1 begins, joint | Part B standard premium |
|---|---|---|---|---|
| 2025 | 2023 | above $106,000 | above $212,000 | $185.00 |
| 2026 | 2024 | above $109,000 | above $218,000 | $202.90 |
Source: CMS fact sheets, announced November 8, 2024 (2025) and November 14, 2025 (2026).
That was a $3,000 climb in the single first threshold and $6,000 in the joint one, in a single year.
Are IRMAA brackets adjusted for inflation?
Yes, and only since 2020. The first four tiers were frozen against inflation from 2011 through 2019 under the Affordable Care Act, then began re-indexing annually; a separate 2018 change (MACRA, below) reshaped the upper breakpoints during that freeze, and the top tier stays frozen to this day, not scheduled to move until 2028.
The surcharge itself is older than the indexing. IRMAA on Part B started in 2007 under the Medicare Modernization Act of 2003, and the Part D surcharge was added in 2011 by the Affordable Care Act, the same law that then held the income lines flat for the rest of the decade. MACRA compressed the upper tiers beginning in 2018, and the Bipartisan Budget Act of 2018 created the $500,000 and $750,000 top tier that took effect in 2019. Only in 2020 did annual inflation adjustment of the first four tiers switch on.
The yardstick is CPI-U, the consumer price index for all urban consumers, U.S. city average, not seasonally adjusted, measured over the 12 months ending each August; each year rescales the 2019 base thresholds by that growth and rounds to the nearest $1,000 (42 U.S.C. §1395r(i)(5)). The $500,000 and $750,000 top tier is the lone holdout: the 2018 law that created it leaves it out of the indexing until 2028. The year-by-year computation, including the raw CPI readings that will set the next round of thresholds, is worked out in full on the 2027 IRMAA brackets page.
When does the new amount take effect?
January 1, and it holds through December. CMS publishes the next year's figures first, in recent practice in November: November 14, 2025 for the 2026 numbers, November 8, 2024 for 2025. SSA's letter follows the same month, and the premium itself changes with the new year. The IRMAA calculator places any 2024 MAGI in its 2026 tier, and every 2026 table, single through separate, is on the 2026 IRMAA brackets page.
What if your income dropped two years ago?
Because the surcharge reads a return two years old, a drop in income reaches the premium on that same two-year delay, and the yearly redo applies it with no paperwork at all. Picture a filer whose 2023 return landed in the second tier: their 2025 premium carried a $185.00 monthly Part B surcharge on top of the standard amount. Say their 2024 income then fell to at or below $109,000 single or $218,000 joint. The determination that sets 2026 reads that lower 2024 return and bills only the standard $202.90, surcharge gone. No form is filed; the lower return simply rotating into the two-year window is what removes the charge.
Form SSA-44 exists for the case this does not cover: income that falls after a qualifying life event, where waiting two years for the return to catch up is the problem. The form reports an estimate of the reduced current-year MAGI so the surcharge can come off ahead of the lag rather than after it.
What happens if you file an amended return?
An amended return opens what SSA calls a new initial determination. That is a different track from a formal appeal, and it carries no 60-day clock; the formal reconsideration route, Form SSA-561-U2, is the one bound by that window. To act on an amended return SSA wants two things: the amended return itself and either the IRS acknowledgment letter or a tax transcript confirming it. With those, SSA re-prices the affected year from the corrected MAGI.
Three grounds all live on this same correction track, and they share one theme: the income record SSA used was wrong. An amended return, an IRS transmission error, and a return newer than the one SSA had on hand each qualify. Keep them separate from the life-event route above: those grounds fix a mistaken record, while Form SSA-44 addresses income that genuinely came down after an event. The IRMAA appeal guide sets out the evidence each correction ground needs.
What if the IRS has not sent your latest return yet?
SSA's manual ties the lookback to "the most recent tax information [that] IRS is able to provide," generally the two-year-old return but never older than three years. Timing creates a gap here. If the two-year-old return has not yet reached SSA when the determination runs, the decision reverts to the three-year-old return, and that older figure can place someone a full tier away from where their real income belongs.
The remedy is built in and needs no life event, because nothing about the income changed; the file was merely incomplete. Once the two-year-old return exists at the IRS, handing it to SSA reopens the year on the newer figure. Concretely: a 2026 determination made before the 2024 return had finished processing reads the 2023 return instead; when the 2024 return is on file, providing it to SSA produces a fresh 2026 determination on 2024 MAGI. Which income lines feed that figure is laid out on the MAGI for IRMAA page.
The annual redetermination rule comes from SSA POMS HI 01101.010 and HI 01120.001, the indexing formula from 42 U.S.C. §1395r(i)(5), and the premium figures from the CMS announcements dated above.