Which tax return (2023 or 2024) does Medicare use to set 2025 IRMAA surcharges?
Executive summary
Medicare’s IRMAA surcharges for 2025 are determined using your modified adjusted gross income (MAGI) from your 2023 federal tax return—i.e., the IRS data two years prior—so the 2023 return is the relevant one for 2025 IRMAA [1] [2]. The Social Security Administration (SSA) normally uses tax information that is two years old, but it can in some cases use earlier returns or accept a request to use a different year via Form SSA-44 if life changes or IRS timing issues arise [3] [4].
1. How IRMAA timing works: the two‑year lookback
Medicare’s IRMAA is calculated from your MAGI reported on the federal tax return two years before the premium year; therefore what you filed for 2023 determines whether you owe IRMAA in 2025 [2] [5]. Multiple practical explainers—Kiplinger, NerdWallet, Healthline and others—describe the same two‑year lag: the SSA obtains IRS data for the tax year that’s two years prior to the IRMAA year and applies those MAGI numbers to set Part B and Part D surcharges [1] [2] [5].
2. Exceptions and administrative quirks the public doesn’t always know
The SSA can sometimes be forced to use tax information from three years prior if the IRS cannot provide the two‑year‑old data, and beneficiaries can ask to have a different year considered using the SSA‑44 life‑changing event form [3] [4]. Sources note the IRS‑to‑SSA data flow and occasional timing mismatches as a reason the SSA might rely on an older return in limited cases [3] [4].
3. Practical implications for taxpayers and planners
Because 2025 IRMAA is based on 2023 MAGI, taxable actions you took in 2023—Roth conversions, large capital gains, or one‑time bonuses—can trigger higher Medicare surcharges two years later [6] [7]. Financial advisers and outlets caution that taxpayers should plan distributions and conversions with the two‑year lag in mind to avoid unintended IRMAA exposure [7] [8].
4. How to dispute or change an IRMAA determination
If your income dropped due to a “life‑changing event” (death of a spouse, marriage, divorce, loss of income, etc.), you can file Form SSA‑44 to request a redetermination and provide supporting documents; the SSA also allows appeals if the IRS data are incorrect or outdated [3] [9]. Humana and other guides emphasize that appeals are an option and that you must provide evidence of the changed circumstance to get the SSA to use a different year or correct an error [9] [3].
5. Why reputable explainers all say the same thing
Commercial and nonprofit explainers (Kiplinger, NerdWallet, Healthline, MedicareResources, and others) converge on the core fact: IRMAA uses MAGI from two years prior, so 2023 tax returns determine 2025 surcharges [1] [2] [10] [5]. That consensus reflects the SSA’s standard operating practice of requesting IRS tax return information two years prior when making annual IRMAA determinations [4].
6. Remaining limits and unanswered specifics
Available sources consistently describe the two‑year rule and list the SSA’s exception/appeal process, but they do not provide a comprehensive checklist of every scenario in which the SSA will accept a different tax year short of the SSA‑44 process—“available sources do not mention” every possible administrative exception beyond the ones cited [3] [4]. Also, while many outlets give specific 2025 surcharge amounts and thresholds tied to 2023 MAGI, details may change annually as CMS updates brackets [1] [6].
Bottom line: if you want to know whether you’ll pay IRMAA in 2025, look at your MAGI on your 2023 tax return; if 2023 contained unusual income you can’t undo now, consider filing SSA‑44 or an appeal if your circumstances changed or if you believe SSA used incorrect data [2] [3].