Every number on IRMAA Hub comes from official CMS and SSA sources. This page explains exactly how the calculator works, which documents our figures come from, when we update them, and how we label years that have not been finalized yet.
The calculator is a pure function: it takes three inputs (your modified adjusted gross income (MAGI), your filing status, and the coverage year) and returns your IRMAA tier, your total Part B premium, your Part D surcharge, and how far you are from the next bracket. It does not store or transmit your income; the calculation runs in your browser.
Medicare uses the most recent tax return on file, which runs two years behind, so your MAGI from two years prior determines the premium for the coverage year. The brackets are cliffs: crossing a threshold by one dollar moves your entire surcharge up to the next tier for the full year. We map your MAGI to the correct tier for your filing status and add the published surcharge to the standard Part B premium.
The bracket thresholds, surcharge amounts, and standard premiums are taken directly from these primary sources:
The standard 2026 Part B premium we use is $202.90 per month, matching the CMS figure.
CMS and SSA publish the official premiums and IRMAA brackets each fall (typically in November) for the following calendar year. We update IRMAA Hub when those figures are released and record a “last verified” date on each data page so you can see how current the numbers are.
For years CMS has not yet finalized (for example, 2027 and 2028), we show projected estimates based on published inflation trends. These pages are clearly labeled as projections, not official figures, and are replaced with the official amounts as soon as CMS publishes them.
Sources: CMS 2026 Medicare Parts A & B Premiums and Deductibles Fact Sheet; SSA POMS HI 01101.020 (IRMAA Sliding Scale Tables); SSA Publication 05-10536. Last verified June 2026.
Informational only. This is not financial, tax, or insurance advice. IRMAA Hub is independent and not affiliated with the U.S. government, Medicare, CMS, or the SSA. For enrollment help, contact Medicare.gov, 1-800-MEDICARE, or your State Health Insurance Assistance Program (SHIP).