The ordinary sequence
For 2026 Medicare premiums, SSA generally uses modified adjusted gross income from the 2024 federal return. A 2026 Roth conversion, capital gain, or required minimum distribution generally appears on the 2026 return, so its ordinary Medicare effect arrives in 2028 rather than in the same calendar year.
That timing does not mean SSA predicts income two years ahead. It uses tax information already filed and available from the IRS. If the preferred year's information is unavailable, SSA can use an older return and later update the determination when newer data arrives.
MAGI is not take-home income
For IRMAA, modified adjusted gross income is generally adjusted gross income plus tax-exempt interest. Cash that never reaches AGI is treated differently from a taxable IRA distribution or realized gain. Conversely, a deduction below AGI may reduce taxable income without reducing IRMAA MAGI.
A planning timeline
| Year | Event | Planning question |
|---|---|---|
| 2024 | Tax return income | Usually determines 2026 IRMAA. |
| 2026 | Conversion, gain, RMD, or work income | Usually appears on the 2026 return. |
| 2028 | Potential Medicare premium effect | Official 2028 tiers will be published later. |
Do not use today's published thresholds as guaranteed thresholds two years from now. Use them to understand sensitivity, then revisit the plan after CMS publishes the premium-year table.
When current income is lower
A beneficiary may request a lower determination after one of the life-changing events listed by SSA and a reduction in MAGI. The request uses Form SSA-44 and requires evidence of the event and reduced income. A normal market loss or a voluntary asset sale is not automatically one of the listed events.
What to keep
Keep the Medicare notice, relevant federal returns, Form 1099-R records, conversion statements, proof of tax-exempt interest, and documents supporting any life-changing event. The notice includes appeal rights and identifies the information SSA used.
Sources: SSA POMS HI 01120.001, Form SSA-44, and SSA lower IRMAA guidance.
Last reviewed August 16, 2026.