Medicare IRMAA costs in plain numbers

IRMAA (Income-Related Monthly Adjustment Amount) is an extra amount some Medicare beneficiaries pay for Part B and Part D when modified adjusted gross income (MAGI) exceeds published thresholds. Thresholds and monthly add-ons are set by CMS and applied by SSA.

For 2026, a married couple filing jointly can face household IRMAA from $0 (standard) up to about $13,872/year at the top tier if both spouses pay IRMAA — with the first non-zero joint tier around $2,297/year. Those round numbers come from CMS monthly Part B + Part D add-ons × 12 × two beneficiaries (research/verify_irmaa_2026.py).

IRMAA generally looks at MAGI from two years prior. A large Roth conversion in year T can raise MAGI and, with a lag, raise Medicare premiums. That lag and the cliff-like brackets are why people model MAGI carefully — not because a website should tell them to convert or not convert.

Use the free IRMAA cliff calculator to map an estimated MAGI to a bracket and see the arithmetic. Treat the output as a worksheet, not a decision.

Primary source: CMS 2026 Medicare premiums fact sheet.