A Roth conversion moves money from a pre-tax retirement account (traditional IRA, and in some plans a traditional 401(k) via plan rules or rollover path) into a Roth IRA. You generally owe ordinary income tax on the converted amount in the year of the conversion. Future qualified Roth withdrawals can be tax-free. Custodians such as Fidelity, Vanguard, and Schwab process conversions; the tax bill is yours to plan for, not theirs.
Account wrappers first: Roth IRA vs 401(k) starter, Roth vs traditional IRA taxes, and Taxable vs tax-advantaged accounts. High earners blocked from direct Roth IRA contributions sometimes pair a non-deductible IRA contribution with a conversion. See Backdoor Roth basics. This guide is orientation only, not a recommendation to convert. Timing tradeoffs (bracket room, cash for tax, when to wait): When should I convert a traditional IRA to Roth.
What a conversion is (and is not)
| Conversion | Contribution | |
|---|---|---|
| Direction | Pre-tax balance → Roth | New cash into a Roth (subject to income/contribution limits) |
| Tax now | Usually taxable as ordinary income | Roth contributions are after-tax; no immediate deduction |
| Annual limit | No IRS “conversion limit,” but tax and bracket math matter | Annual contribution caps apply |
A backdoor Roth (non-deductible traditional IRA contribution, then convert) is a related strategy with pro-rata rules. Confirm current IRS Publication 590-A/B language and Form 8606 filing before you assume it is simple (Filing taxes for beginners).
Why people consider conversions
- They expect higher tax rates later than this year.
- A low-income year (job gap, parental leave, early retirement before Social Security) leaves room in lower brackets.
- They want to reduce future required minimum distributions on traditional balances.
- Estate or beneficiary planning where heirs may prefer Roth dollars (rules change. Verify current law).
None of those reasons overrides: can you pay the tax from non-retirement cash? Using IRA dollars to pay the conversion tax shrinks the amount that compounds.
Worked example
Alex has $40,000 in a traditional IRA at Vanguard and $12,000 in a taxable brokerage HYSA-equivalent cash sleeve for taxes. Taxable income this year is unusually low after a mid-year job change. Alex converts $15,000.
- Conversion adds ~$15,000 of ordinary income on the return.
- At a blended ~22% federal marginal rate (illustrative), federal tax ≈ $3,300; state tax may add more.
- Alex pays the ~$3,300 from the cash sleeve, not from the IRA, so the full $15,000 can sit in the Roth.
- If Alex had converted $40,000 without cash for taxes, the bracket jump and a forced IRA withholding could erase much of the point.
Employer match still comes first while working (Employer 401(k) match). Do not skip a match to “free up” conversion cash.
Timing and mechanics cues
- Ask the custodian for the conversion form; choose cash or in-kind shares.
- Track cost basis and prior non-deductible contributions (Form 8606 history).
- Estimate the year’s taxable income before you convert a large block, partial conversions across years are common.
- Note the five-year rules that can apply to converted amounts withdrawn early (separate from the five-year clock on Roth contribution earnings), side-by-side: Roth IRA 5-year rules.
- Once you reach your required beginning date for RMDs (SECURE 2.0: often age 73 or 75 by birth year, not the old 70½ rule), conversions and RMD sequencing interact; take any RMD first and confirm current IRS timing before you convert dollars you must distribute anyway (Required beginning date for RMDs).
Fund choice inside the Roth is the same long-term problem as anywhere else: low-cost diversified funds (Investing basics for beginners).
When conversions are usually a poor fit
- You would need to sell emergency reserves or carry a credit-card balance to pay the tax.
- You are already in a high bracket and expect lower income later.
- You need the money in fewer than five years.
- You have not mapped the rest of the stack (match, emergency fund, high-interest debt).
Some plans convert after-tax 401(k) dollars in-plan (mega backdoor): Mega backdoor Roth basics.
Checklist
- Sketch this year’s taxable income and room in lower brackets.
- Confirm the source account allows conversion or rollover-to-IRA then convert.
- Calculate tax with a preparer or reputable software before you click confirm.
- Pay tax from non-IRA cash when possible.
- File Form 8606 when required; keep confirmation PDFs.
- Revisit RMDs and beneficiary forms after large moves.
Nondeductible IRA contribution plus conversion walkthrough: Backdoor Roth IRA basics.
The same low-income year you might convert to Roth can also be used to harvest taxable-account gains at 0% LTCG rates: Tax-gain harvesting basics.
Staggered conversions for early access, five-year clocks and ladder pitfalls: Roth conversion ladder basics.
Sizing conversions when wages drop: How to plan Roth conversions in a low-income year.
Pre-tax IRA balances make conversions partly taxable under aggregation rules: Roth conversion pro-rata basics.
Over-contributed to an IRA and need a corrective distribution instead of a conversion: IRA excess contribution removal basics.
Educational only. Not tax, investment, or legal advice. Conversion rules, contribution limits, and RMD ages change; confirm on IRS.gov and with a qualified tax professional before you act.