How to use the IRMAA calculator
- Pick the premium year. 2027 premiums are set by your 2025 tax return, 2026 premiums by your 2024 return: Social Security looks back two years.
- Choose the filing status on that return and enter its adjusted gross income and tax-exempt interest. Together they are the modified adjusted gross income (MAGI) Social Security uses.
- Tick drug coverage if you have a Part D plan or a Medicare Advantage plan with drug coverage, and on a joint return whether both of you are on Medicare.
- Read the tier, the monthly Part B premium and the yearly surcharge, then the line under them: how much more income keeps you in the bracket and what crossing the next edge would cost.
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How IRMAA works
The income-related monthly adjustment amount (IRMAA) is an extra charge on Medicare Part B and Part D for people with higher incomes. Most people pay the standard Part B premium, $202.90 a month in 2026, which covers about 25% of what Part B costs. With IRMAA you pay 35%, 50%, 65%, 80% or 85% of the cost instead, depending on your tier, so the total Part B premium runs from $284.10 to $689.90 a month. Part D adds a flat $14.50 to $91.00 a month on top of whatever your plan charges.
Social Security decides the tier from the return the IRS sends it and tells you by letter. The surcharge is taken out of your Social Security payment, or billed by Medicare if you don't get benefits yet. It is set again every year, so a high-income year raises premiums for one year, two years later, and falls away after that.
The cliff: why $1 matters
IRMAA isn't phased in. Each tier begins at an exact MAGI and charges its full amount from the first dollar over the edge. On a 2026 individual return, $109,000 of MAGI pays the standard premium and $109,001 pays tier 1: $1,148.40 more a year with drug coverage. That's why the calculator shows the distance to the next edge and the room left in each bracket. If you are planning a Roth conversion, a property sale or a large IRA withdrawal, it tells you how much fits before the next tier, as long as you remember that income from 2026 sets the 2028 premiums, whose brackets are published only in late 2027.
The edges change from year to year: the first individual edge rose from $106,000 for 2025 premiums to $109,000 for 2026 (SSA POMS HI 01101.020). Married couples filing separately who lived together at any point in the year use a much harsher table: anything over $109,000 is tier 4.
2027 figures: what is confirmed
As of October 18, 2026, CMS had not published the 2027 Part B premium, deductible or IRMAA brackets. It announced the 2026 figures on November 14, 2025, and usually publishes the next year's in November. Until then, the 2027 option uses the official 2026 figures and marks them provisional; this page is updated when CMS publishes. The standard premium and the bracket edges both changed from 2025 to 2026, so treat a result close to an edge as uncertain until then.
If your income has dropped
Because the income is two years old, retirement can make IRMAA look too high: you may have stopped working since. Social Security can use a more recent year's income if a life-changing event lowered it. You request this with Form SSA-44 (online, by mail or fax, or at an office), with proof of the event and of the lower income. If Social Security used the wrong income, or you amended the return, ask for a correction instead.
To see what your Social Security check will look like after the 2027 cost-of-living raise and the Part B premium, try the Social Security COLA calculator. The interest calculator shows what savings earn (interest counts toward MAGI for IRMAA, taxable or tax-exempt), and the printable calendar helps you mark when the IRMAA letter and the open enrollment period arrive.
Sources, checked October 18, 2026: CMS, 2026 Medicare Parts A & B Premiums and Deductibles (Part B and Part D IRMAA tables); SSA, Premiums: Rules for Higher-Income Beneficiaries; SSA, POMS HI 01101.020 IRMAA Sliding Scale Tables and HI 01120.060 Married, Filing Separately – Lived Apart All Year; SSA, Request to lower IRMAA.