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.
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.
- After 70½/RMD age rules, conversions and RMD sequencing interact; get current IRS timing right before you move dollars you must distribute anyway.
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.
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.