The IRMAA two-year look-back, explained with dates

Your Medicare Part B and Part D premiums in any year are set by the MAGI on your tax return from two years earlier. Income decisions made today show up in premiums two years from now, and the income that sets your premium today is already history.

Which income year sets which premium year
Income (tax) year	Return filed in	Premium year	Brackets
2024	2025	2026	published
2025	2026	2027	projected
2026	2027	2028	not yet known
2027	2028	2029	not yet known
2028	2029	2030	not yet known

When the look-back hurts: three typical cases

1. Retiring

A single person earning a salary that brings MAGI to $240,000 in 2024, retiring early in 2025, pays 2026 premiums on the salary year: tier 4, $649.20 a month for Part B plus $83.30 for Part D. Stopping work is a life-changing event: with Form SSA-44, SSA can use the 2025 or 2026 income instead. See the SSA-44 worksheet.

2. Selling a home or a business

A large one-time gain lifts MAGI for one tax year, and so one premium year, two years later. It is not a qualifying event. If you can choose the timing, look at which premium year it will land in and at how far above the next threshold it takes you.

3. Losing a spouse

This is where the look-back combines with the change of table. A married couple filing jointly with $200,000 of MAGI pays no irmaa in 2026 (the joint threshold is $218,000). If one spouse dies and the survivor later files as single with $150,000 of income — less than before — the individual table applies, with thresholds half as high: tier 2, $2,884.80 a year.

For the year of the death, the IRS still treats the survivor as married and allows a joint return (IRS Publication 501).
Death of a spouse is a life-changing event. If the new income and status lower the tier, the survivor can ask SSA to use a more recent year with Form SSA-44. If they raise it, the change reaches premiums through the normal look-back.
A qualifying surviving spouse with a dependent child uses the same individual table as a single filer.

The yearly calendar

January: new Part B premium and IRMAA brackets apply; the COLA arrives in the January payment.
By March 31: last day to ask SSA to cover the previous premium year when a life-changing event happened between October 1 and December 31 of that year.
April 15: federal returns due. The return you file now sets premiums in two years.
Each month, between the 10th and the 14th in 2026: the BLS publishes the CPI; July, August and September decide the COLA. The September 2026 figure comes out on October 14, 2026.
Late September to mid-November: CMS publishes the next year’s Part B premium and IRMAA brackets (between September 27 and November 14 over the last seven years).
Late November: SSA posts COLA notices in my Social Security accounts (as it did for 2026).

Frequently asked questions

Why does SSA use income from two years ago?

Because the law says so: MAGI is “determined for the individual’s last taxable year beginning in the second calendar year preceding the year involved” (Social Security Act §1839(i)(4)). If, as of October 15 of the year before, the IRS does not have that return in usable form, SSA uses the return from the year before it, and corrects once the newer data arrive.

I just enrolled in Medicare at 65. Can I owe IRMAA?

Yes, from the first month: premiums at 65 are based on the tax return for the year you turned 63.

We sold our house and had a big capital gain. What happens?

The taxable part of the gain is in your AGI, so it counts in MAGI for the premium year two years later. SSA lists capital gains from selling property as one-time income that is not a life-changing event: you cannot use Form SSA-44 to have it ignored. It affects one premium year only, if the rest of your income stays lower.

Does SSA automatically update when my income goes down?

Yes, eventually: each year SSA receives newer IRS data and recalculates. Form SSA-44 only speeds this up by one or two years when a qualifying event caused the drop.

Official sources

Sources read on September 29, 2026.

Page updated September 29, 2026. Official figures checked against CMS and SSA on September 29, 2026.