Roth Conversion Calculator

Calculate tax cost of converting traditional IRA to Roth IRA in 2026. Compare paying tax now vs later — pre-retirement window strategy. Cite official methodology in your communications — sources linked below.

How the Calculation Works

Roth conversion moves money from traditional IRA/401k (pre-tax) to Roth IRA — you pay ordinary tax on the conversion amount now, in exchange for tax-free growth and tax-free withdrawals in retirement. Useful when current tax bracket is LOWER than future bracket (early retirement, between jobs, low-income years).

Benchmarks and Use Cases

Best conversion windows: gap years between employment, early retirement before Social Security/RMDs kick in (age 60-72), market downturns (smaller conversion = smaller tax). Roth conversions also reduce future RMDs (after age 73 — no RMDs on Roth IRAs). For high-income current earners, consider partial conversions to fill up current bracket without jumping to higher one.

Common Mistakes and Limitations

Common mistakes: (1) Converting in high-income year — pays more tax now than would have paid later. (2) Failing to pay tax from OUTSIDE the conversion (paying from converted dollars reduces growth opportunity). (3) Forgetting 5-year rule on converted amounts before age 59.5. (4) Doing in December without checking effect on IRMAA premiums 2 years later.

Last updated May 2026. Sources: IRS, IRS Pub 590-A.