How much tax will a conversion cost me?

The converted pre-tax amount is added on top of the year's other income and taxed at ordinary federal rates. Because US brackets are progressive, the conversion is taxed across every bracket it spans — not at a single rate.

Income stacking

A conversion "stacks" on top of ordinary income. Example (2026, single filer): someone with $60,000 of taxable income who converts $50,000 has $110,000 of taxable income. The conversion dollars fill the remainder of the 22% bracket (which tops out at $105,700 of taxable income for single filers in 2026) and spill into the 24% bracket. The conversion's effective rate is a blend of 22% and 24% — not the 22% rate the person "was in" before converting.

A common error is multiplying the conversion by the pre-conversion marginal rate. The correct computation is incremental: tax on (income + conversion) minus tax on (income alone).

2026 federal brackets (taxable income upper bounds)

Single: 10% to $12,400 · 12% to $50,400 · 22% to $105,700 · 24% to $201,775 · 32% to $256,225 · 35% to $640,600 · 37% above.

Married filing jointly: 10% to $24,800 · 12% to $100,800 · 22% to $211,400 · 24% to $403,550 · 32% to $512,450 · 35% to $768,700 · 37% above.

Head of household: 10% to $17,700 · 12% to $67,450 · 22% to $105,700 · 24% to $201,775 · 32% to $256,200 · 35% to $640,600 · 37% above.

2026 standard deductions: $16,100 single · $32,200 married filing jointly · $24,150 head of household. Taxable income is gross income minus deductions, so the room below a bracket top is measured after the standard (or itemized) deduction.

Filling to the top of a bracket

A bracket-aware strategy converts only enough to reach the top of the current bracket, avoiding spillover into the next rate. Example (2026, married filing jointly): with $150,000 of taxable income, converting $61,400 exactly fills the 22% bracket ($211,400 top). Converting more than that pushes the excess into 24%. Repeating this each year over several years converts a large balance without ever paying the higher rate — the basis of staged conversion plans.

Beyond the bracket rate (second-order effects)

Conversion income raises adjusted gross income, which can trigger effects outside the bracket table: higher Medicare premiums via IRMAA (based on income from two years prior), the 3.8% net investment income tax threshold, taxation of Social Security benefits, and loss of income-based credits or subsidies. State income tax typically applies as well. These are commonly evaluated separately from the federal bracket math.