A Roth conversion is a retirement tax move that many investors take the time to understand, and here is what you need to know: you move pre-tax money from a Traditional IRA, SEP IRA, SIMPLE IRA, or 401(k) into a Roth IRA, pay ordinary income tax on the converted amount this year, and then own an account that grows and pays out tax-free. This guide covers the rules, the tax math, the timing, and the traps in plain English so you can decide whether a conversion fits your plan.
A Roth conversion moves money from a pre-tax retirement account (Traditional IRA, SEP, SIMPLE, or 401(k)) into a Roth IRA. The converted amount is added to your taxable income for the year and taxed at your ordinary marginal rate. There is no income limit and no dollar cap, the move is irreversible, and the December 31 deadline is firm. In return, future growth and qualified withdrawals are tax-free, and Roth IRAs have no lifetime required minimum distributions.
What is a Roth conversion?
A Roth conversion is the act of transferring pre-tax retirement savings into a Roth IRA and paying the income tax owed on that amount now, so the money can grow and be withdrawn tax-free later. It is not a contribution and it is not capped by the annual IRA limit. This page is the full guide.
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The trade is simple to state. You accept a known tax bill today in exchange for tax-free income and no future required withdrawals. Whether that trade helps you depends on your current tax bracket, your expected bracket in retirement, and how the extra income interacts with Medicare and Social Security.
Unlike a Roth contribution, a conversion has no income ceiling. High earners who are shut out of direct Roth contributions (the 2026 contribution phase-out runs from $153,000 to $168,000 of MAGI for single filers and $242,000 to $252,000 for joint filers) can still convert any amount they choose. Q3 Advisors focuses on Roth conversion planning as part of a broader retirement tax strategy.
How does a Roth conversion actually work, step by step?
A Roth conversion works by instructing your custodian to move a chosen dollar amount from a pre-tax account into a Roth IRA. The custodian reports the amount on Form 1099-R, you report it as income, and you pay the tax when you file (or through estimated payments). You can convert Traditional, SEP, and SIMPLE IRAs and, if your plan allows, 401(k) dollars. You choose how much to convert each year.
Which accounts can I convert (Traditional, SEP, SIMPLE, 401(k))?
You can convert almost any pre-tax retirement account into a Roth IRA. Eligible sources include Traditional IRAs, SEP IRAs, SIMPLE IRAs (after a two-year participation window), and workplace 401(k), 403(b), and 457(b) plans when the plan permits in-service conversions or after you separate from the employer.
One amount can never be converted: a required minimum distribution. If you are RMD age, you must take the RMD first, and only dollars above the RMD may be converted. Deciding how much to convert to a Roth each year is where most of the planning value sits.
What does the conversion process look like?
The mechanics are short once the planning is done. After you decide how much to convert for the year, the paperwork itself usually takes only a few days to complete. You instruct the custodian, the money moves from the pre-tax account into the Roth IRA, and the tax reporting follows at filing time. The four steps below walk through the sequence, from settling on an amount to keeping the right forms for your return.
- Confirm the dollar amount that keeps you inside your target tax bracket for the year.
- Tell your IRA custodian or plan administrator you want a Roth conversion (not a rollover to another pre-tax account).
- Decide whether tax is withheld from the conversion or paid separately (many investors pay the tax from outside funds; see below).
- Keep the Form 1099-R and Form 5498 the custodian issues, and report the conversion on Form 8606 when you file.
How much tax will I pay on a Roth conversion?
You pay ordinary income tax on the full converted amount at your marginal rate for the year. Convert $10,000 while in the 22% bracket and you add roughly $2,200 in federal tax. Large conversions can push part of the amount into a higher bracket, so many investors convert in partial slices. State income tax and the two-year Medicare (IRMAA) lookback can add to the real cost.
How is the converted amount taxed (ordinary income, marginal-rate example)?
The converted dollars stack on top of your other income and are taxed at ordinary income rates, not capital gains rates. A Roth conversion is not itself net investment income, so it does not directly trigger the 3.8% net investment income tax, though the added income can push other investment income over the $200,000 single or $250,000 joint NIIT thresholds.
Because the tax follows your bracket, the marginal rate matters more than the average rate. Here are the 2026 federal brackets that frame most conversion decisions.
| 2026 marginal rate | Single taxable income | Married filing jointly |
|---|---|---|
| 22% | starts at $50,400 | starts at $100,800 |
| 24% | up to $201,775 | up to $403,550 |
| 32% | starts at $201,775 | starts at $403,550 |
| 35% | starts at $256,225 | starts at $512,450 |
| 37% | starts at $640,600 | starts at $768,700 |
Example: a single filer with $60,000 of taxable income sits in the 22% bracket, which for a single filer runs to about $105,700 in 2026. Converting $50,000 would raise taxable income to $110,000, so most of the conversion is taxed at 22% while the top slice of roughly $4,300 crosses into the 24% bracket, for about $11,100 in added federal tax. Sizing the conversion to stop near the top of the 22% band is the kind of bracket question a Roth conversion break-even analysis is designed to weigh.
Should I pay the tax from my IRA or from outside funds (the under 59 1/2 withholding trap)?
Many investors pay the conversion tax from outside, non-retirement money whenever they can. If you withhold the tax from the IRA itself, that withheld amount never lands in the Roth, so less of your money keeps growing tax-free. Paying from a taxable brokerage or savings account lets the full converted balance stay invested inside the Roth.
There is a sharper trap under age 59 1/2. Any amount withheld for taxes from the IRA is treated by the IRS as an early distribution, so it is taxed and hit with a 10% penalty on top. A younger investor who converts $50,000 and withholds $11,000 for tax can owe an extra $1,100 penalty on that withheld piece. Paying the tax from outside funds avoids the penalty entirely.
How do state taxes change the math?
State income tax is added on top of the federal bill, and the range is wide. A conversion taxed at a 22% federal rate can cost several points more in a high-tax state and nothing extra in a no-income-tax state, so where you live (and where you plan to live in retirement) belongs in the decision.
| Example state | Top state income tax rate | Effect on a conversion |
|---|---|---|
| Texas or Florida | 0% | Federal tax only on the converted amount |
| Pennsylvania | 3.07% | Modest state tax added |
| California | up to 13.3% | State tax can materially raise the total cost |
If you expect to move from a high-tax state to a no-tax state after you retire, waiting to convert until after the move can lower the state portion of the bill. This is a general pattern, not advice for your situation.
When does a Roth conversion make sense?
A Roth conversion often makes sense when your current tax rate is lower than the rate you expect to pay later. A window many retirees consider is the low-income stretch between leaving work and the start of Social Security and required minimum distributions. Down markets and unusually low-income years also lower the tax cost of converting a given number of shares.
What is the Roth conversion corridor (the retirement to RMD window)?
The Roth conversion corridor is the low-income window that often opens after you stop working but before Social Security and RMDs begin. In those years, taxable income can drop sharply, which can leave room in the 12%, 22%, or 24% brackets to convert at a lower rate than you will face once RMDs start.
The corridor matters because required minimum distributions now begin at age 73 under SECURE 2.0 (rising to age 75 for people born in 1960 or later, with the earliest age-75 RMD year being 2035). Filling the low brackets during the corridor can shrink the Traditional balance that would otherwise force large taxable RMDs later.
Do low-income years and market downturns help?
Yes on both counts. A year with low taxable income (a gap between jobs, an early retirement year, a year with large deductions) lets you convert more before hitting the next bracket. A market downturn helps in a different way: when account values are down, the same number of shares carries a smaller dollar value, so you convert more shares for the same tax and capture the recovery inside the Roth.
Partial or laddered conversions combine both ideas. Instead of converting a large balance in one year and spiking into a high bracket, many investors convert a measured slice each year to stay under a chosen threshold.
What is the 5-year rule for Roth conversions?
The 5-year rule for conversions says each converted amount must sit in the Roth for five years before you can withdraw that converted principal penalty-free if you are under 59 1/2. The clock starts on January 1 of the conversion year, and every conversion has its own five-year window. Once you are 59 1/2 or older and your first Roth has been open five years, qualified withdrawals of earnings are fully tax-free.
There are two separate five-year clocks, which is where confusion starts. One clock governs tax-free earnings and starts with your first-ever Roth contribution or conversion. A second clock applies to each conversion and governs the 10% early-withdrawal penalty on converted principal for those under 59 1/2.
| Conversion year | Five-year clock starts | Converted principal available penalty-free (if under 59 1/2) |
|---|---|---|
| 2026 (converted in December) | January 1, 2026 | January 1, 2031 |
| 2027 | January 1, 2027 | January 1, 2032 |
If you are already 59 1/2 or older, the per-conversion penalty clock stops mattering, because the 10% early-distribution penalty no longer applies. For a deeper walkthrough, see our full explainer on the Roth conversion 5-year rule.
How does a Roth conversion affect Medicare (IRMAA) and Social Security?
A Roth conversion raises your modified adjusted gross income (MAGI), which can push more of your Social Security into the taxable range (up to 85% of benefits) and can trigger Medicare income-related surcharges (IRMAA) on Part B and Part D. IRMAA uses a two-year lookback, so a 2026 conversion can raise your 2028 premiums. The thresholds behave like cliffs, not gentle slopes.
Why does a conversion today raise my Medicare premiums two years later?
Medicare sets each year’s premium using your tax return from two years earlier. A conversion in 2026 shows up on your 2026 return, which Medicare reads in 2028, so a conversion today can raise premiums two years out. The last conversion year that never touches a Medicare premium is the year you turn 62, because premiums begin at 65.
IRMAA is a cliff, not a slope. In 2026 the standard Part B premium is $202.90 per month, and the first surcharge tier begins once MAGI passes $109,000 for a single filer or $218,000 for a joint filer. Cross that line by even one dollar and the full surcharge applies for the year, so conversions are often sized to stop just below a tier.
| Item | How a conversion affects it |
|---|---|
| Social Security taxability | Higher MAGI can make up to 85% of benefits taxable |
| Medicare IRMAA (Part B and Part D) | Two-year lookback; a 2026 conversion can raise 2028 premiums once MAGI tops $109k single or $218k joint |
| Net investment income tax | Conversion is not itself NII, but the added income can push other investment income over $200k single or $250k joint |
What are the biggest Roth conversion mistakes to avoid?
The biggest Roth conversion mistakes are converting so much that you jump a tax bracket or an IRMAA tier, withholding the tax from the IRA before age 59 1/2 (which creates a penalty), forgetting the December 31 deadline, and ignoring the two-year Medicare lookback. Assuming a conversion can be undone is also a costly error, because recharacterization of conversions ended after 2018.
- Converting too much in one year and spilling into a higher bracket instead of using partial, laddered conversions.
- Withholding the tax from the IRA under age 59 1/2, which turns the withheld amount into a penalized early distribution.
- Overlooking the IRMAA cliff, so a small overage adds a full year of Medicare surcharges two years later.
- Missing the December 31 cutoff, since there is no conversion equivalent of the April contribution grace period.
- Expecting to reverse it. A conversion completed after 2018 is irreversible; the Tax Cuts and Jobs Act removed recharacterization for conversions.
Who should and who should not consider a Roth conversion?
A Roth conversion may suit investors who expect higher future tax rates, who have low-income years available, who can pay the tax from outside funds, and who want to reduce future RMDs or leave tax-free assets to heirs. It is often a weaker fit for those in a peak earning year, those who would pay the tax from the IRA itself, and those who expect a much lower tax rate in retirement.
| Factor | Often favorable | Often unfavorable |
|---|---|---|
| Current vs future tax rate | Lower rate now than expected later | Peak earning year, lower rate expected later |
| Source of tax payment | Pay from outside, non-retirement funds | Would withhold tax from the IRA |
| Time horizon | Years of tax-free growth ahead | Need the money within a few years |
| Estate goals | Want to leave tax-free assets to heirs | Legacy is not a priority |
One planning note for 2026: the Tax Cuts and Jobs Act rates were made permanent under the 2025 law (OBBBA, P.L. 119-21), so the old urgency to convert before a 2026 rate sunset is gone. That removes an artificial deadline and puts the focus back on your own bracket path. Heirs still face the SECURE Act 10-year rule for inherited IRAs, which can compress a beneficiary’s taxable withdrawals, and a Roth inheritance passes to them without that income tax.
Work with Q3 Advisors
Q3 Advisors is a registered investment adviser focused on retirement tax planning. This page is educational and is not advice; consult a qualified professional.
Frequently asked questions
How much tax will I pay on a Roth conversion?
You pay ordinary income tax on the full converted amount at your marginal rate for the year. Converting $10,000 in the 22% bracket adds about $2,200 in federal tax; state tax may apply on top. Large conversions can push the top slice into a higher bracket, which is why many investors convert in partial amounts to stay inside a target bracket.
At what age does a Roth conversion not make sense?
There is no age that automatically rules a conversion out, but it often makes less sense late in retirement when your tax bracket is already low and the tax-free growth window is short. Converting after age 62 can also raise Medicare premiums two years later through the IRMAA lookback. Many investors weigh a shorter horizon against the immediate tax cost.
How do I avoid paying taxes on a Roth conversion?
You cannot avoid the tax on a conversion entirely; the converted amount is taxable ordinary income. You can reduce the bill by converting in low-income years, staying inside a lower bracket with partial conversions, paying the tax from outside funds, and timing conversions during down markets. Offsetting deductions in the same year can also lower the taxable total.
What is the 5-year rule for Roth conversions?
The 5-year rule requires each converted amount to remain in the Roth for five years before you can withdraw that converted principal penalty-free if you are under 59 1/2. The clock starts January 1 of the conversion year, and each conversion has its own window. Once you are 59 1/2 and your first Roth is five years old, qualified withdrawals of earnings are tax-free.
Is there an income limit for a Roth conversion?
No. Unlike Roth contributions, which phase out in 2026 between $153,000 and $168,000 of MAGI for single filers and $242,000 and $252,000 for joint filers, a Roth conversion has no income limit and no dollar cap. Anyone with a pre-tax retirement account can convert any amount, which is why high earners use conversions when direct Roth contributions are closed to them.
