Roth conversion calculator

How much extra federal tax the conversion adds this year, how much of the 12% / 22% / 24% bracket is left, and whether MAGI crosses a Medicare IRMAA cliff two years later. Brackets from Rev. Proc. 2025-32. IRMAA floors from the CMS 2026 table — a conversion this year hits IRMAA two years out, and those floors will be higher. Read the conversion primer first. This is not the Roth vs traditional contribution widget.

Filing status Taxable income before conversion MAGI before conversion Conversion amount this year

Taxable income is Form 1040 taxable, after the standard or itemized deduction. MAGI for IRMAA is AGI plus tax-exempt interest. They are not the same number.

People on Medicare two years from now Under age 59½ this year? State income tax % (your rate, not a scrape) Other net investment income (NIIT flag)

A conversion is ordinary income, not NII. It can still pull existing NII over the $200k / $250k NIIT MAGI floor (IRC §1411, not indexed).

2026 conversion

—

Federal tax uses 2026 ordinary tables (Rev. Proc. 2025-32). IRMAA extra is Part B + Part D monthly surcharges × 12 × people, from the CMS 2026 table, labeled as a stand-in for the lookback year. Prefill is the worked slice in NOTES: single, taxable $84,000, MAGI $100,000, convert $21,700 to the top of 22%. Sequence: tax-efficient withdrawals. Cliffs only: IRMAA MAGI room. Backdoor is a different tool: backdoor Roth.