Roth Conversion Calculator
The years between retirement and your first RMD (age 73 or 75) are the most valuable planning window most retirees never fully use. This calculator compares your lifetime tax bill — with and without converting traditional IRA assets to Roth — so you can see whether the upfront tax cost pays off for your numbers.
How the comparison works
Both scenarios are projected from your current age through age 90 using the IRS Uniform Lifetime Table (post-SECURE Act 2.0) and 2026 federal tax brackets.
- No-conversion scenario: Your traditional balance grows uninterrupted. RMDs begin at your RMD start age based on the full balance. Each year's federal + state tax on RMDs is accumulated.
- With-conversion scenario: Each pre-RMD year, the annual conversion amount shifts from traditional to Roth. Roth grows tax-free with no future RMDs. Your traditional balance — and future RMDs — shrinks proportionally.
- Upfront cost: The incremental federal + state tax you pay from adding conversions to your income each pre-RMD year. This is the real cost of converting.
- Net savings: RMD taxes saved (age RMD–90) minus upfront conversion cost. Positive = converting saves more than it costs; negative = you're converting too much or into too high a bracket.
- IRMAA triggers. If a conversion raises your MAGI above $109,000 (single) / $218,000 (MFJ) in 2026, Medicare Part B + D surcharges kick in two years later — adding $600–$5,000+/yr. One bracket jump can wipe out a year of conversion savings.
- Social Security taxation. SS benefits become 0–85% taxable as AGI rises. Conversions that push income above the $34K/$44K combined-income thresholds increase SS taxes — an additional upfront cost not reflected here.
- QCD offsets. If you're 70½ or older, Qualified Charitable Distributions let you satisfy RMDs tax-free via direct charitable gifts (up to $111,000/yr in 2026). This reduces the tax burden of not converting.
- Estate planning. Inherited Roth IRAs grow tax-free for 10 years under the SECURE Act 10-year rule. For legacy-focused retirees, conversions often win even when the pure tax math is close.
The Roth conversion window: why timing is everything
When you retire and before Social Security fully kicks in, most retirees are in their lowest income bracket since their 20s. This gap — typically 5 to 12 years — is the conversion window. Once RMDs start, your taxable income rises every year as the IRS Uniform Lifetime Table divisor shrinks and your balance (if well-invested) grows. Converting in the window locks in today's rates on money that would otherwise be distributed at tomorrow's (higher) effective rates.
A 65-year-old couple with $2M in traditional IRA and $60K of other income can convert approximately $140K/year before crossing into the 24% federal bracket. Converting for 8 years (ages 65–72) at the 22% marginal rate moves over $1.1M into Roth. Without conversions, that same money distributed as RMDs in their late 70s and 80s may face a stacked effective rate of 32%+ — because a larger account balance forces larger RMDs, which pile on top of Social Security income and can trigger IRMAA surcharges.
2026 federal tax brackets
The calculator uses 2026 rates (OBBBA-permanent + IRS Rev. Proc. 2025-32 inflation adjustment):
| Rate | Single — taxable income | Married filing jointly |
|---|---|---|
| 10% | Up to $12,400 | Up to $24,800 |
| 12% | $12,400 – $50,400 | $24,800 – $100,800 |
| 22% | $50,400 – $105,700 | $100,800 – $211,400 |
| 24% | $105,700 – $201,775 | $211,400 – $403,550 |
| 32% | $201,775 – $256,225 | $403,550 – $512,450 |
| 35% | $256,225 – $640,600 | $512,450 – $768,600 |
| 37% | Over $640,600 | Over $768,600 |
Standard deduction 2026: $16,100 (single) / $32,200 (MFJ). Source: IRS Rev. Proc. 2025-32; One Big Beautiful Bill Act (OBBBA), July 2025.
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Get a specialist to run your actual numbers
This calculator models federal + state tax on conversions and RMDs. A fee-only RMD specialist layers in IRMAA bracket management, Social Security taxation, QCD integration, asset location, and estate goals — all of which shift the conversion decision. Free match with a specialist who works exclusively on retirement distribution planning.