Reviewed September 2026.
A Roth conversion moves pre-tax traditional IRA dollars into a Roth IRA and usually adds the converted amount to ordinary income this year. Mechanics live in Roth conversions basics. This page is the timing tradeoff: when bracket math, cash for taxes, and future RMDs make a conversion worth considering, and when it does not. Tax brackets and RMD ages change; confirm current IRS rules before you convert.
The decision in one sentence
Convert when you can pay the tax from non-IRA cash, you have room in lower brackets this year, and you expect those dollars to stay invested long enough for the Roth rules to matter (Roth 5-year rule).
Tax flavor of the two IRAs: Roth vs traditional IRA taxes. Workplace context: Roth IRA vs 401(k) starter.
Signals that often favor a partial conversion
| Signal | Why it matters |
|---|---|
| Low-income year (job gap, parental leave, early retirement before Social Security) | More room in 10%/12%/22% federal brackets (illustrative; use current tables) |
| Large traditional balance and years before RMDs | Converting early can shrink future RMD size |
| Taxable cash set aside for the bill | Avoids withholding from the IRA itself |
| Expect higher future tax rate | Paying tax now may be cheaper than later (not knowable with certainty) |
Partial conversions across several years are common. There is no IRS annual “conversion limit,” but ordinary marginal-bracket boundaries and separate IRMAA/Medicare surcharge thresholds can act like soft limits. Crossing an ordinary income-tax bracket taxes only the excess at the higher rate; that is different from a Medicare surcharge cliff.
Signals that usually say wait or skip
- You would charge the tax or drain the emergency fund.
- You are already in a high bracket and expect lower income later.
- You need the money within five years.
- Pro-rata rules would make a “backdoor” conversion messier than you budgeted (Pro-rata basics).
- You have not yet captured an employer match.
Worked example: bracket-room cushion
Sam has $90,000 in a traditional IRA at Fidelity and $10,000 taxable cash earmarked for taxes. Taxable income this year is low after a mid-year layoff. The top of Sam’s current federal bracket has about $18,000 of room before the next rate.
- Sam converts $15,000 (leaves a cushion under the next marginal bracket).
- At an illustrative 22% marginal federal rate, tax ≈ $3,300; state may add more.
- Sam pays ~$3,300 from the cash sleeve so the full $15,000 can sit in the Roth.
- Next year, if income returns to normal, Sam converts $0 or a smaller slice.
Sam does not convert the entire $90,000 in one year and push ordinary income into higher brackets plus a surprise tax bill.
Early-retirement “ladder” planning (separate topic): Roth conversion ladder basics. Year-timing worksheet when income dips: How to plan Roth conversions in a low-income year.
Checklist
- Estimate this year’s taxable income and room under the next bracket.
- Decide the conversion amount before you click confirm at the custodian.
- Pay tax from non-IRA cash when possible.
- File Form 8606 when required; keep conversion confirms.
- Re-check RMD timing if you are near your required beginning date.
- Revisit beneficiaries after large Roth moves.
Educational only. Not tax or investment advice. Brackets, IRMAA, RMD ages, and conversion rules change; confirm on IRS.gov and with a qualified tax professional.