Roth Conversion Tax Strategies: When and How to Convert Your Traditional IRA (2026)
Convert at the right time, in the right amount, and potentially save tens of thousands in lifetime taxes. A complete guide to timing, partial conversions, and tax bracket management.
Updated April 6, 2026
12 min read
Quick Answer
What is a Roth conversion? A Roth conversion transfers money from a Traditional IRA (or other pre-tax retirement account) to a Roth IRA. You pay ordinary income tax on the converted amount in the year of conversion, but all future growth and qualified withdrawals are tax-free. The strategy is most valuable when you can convert during a year your tax rate is lower than what you expect to pay in retirement. For someone converting $100,000 from a Traditional IRA during early retirement in the 22% bracket, the upfront tax cost of approximately $22,000 could save significantly more in taxes over decades of tax-free growth.
A Roth conversion (sometimes called a Roth rollover) moves funds from a Traditional IRA, SEP-IRA, SIMPLE IRA, or eligible employer plan into a Roth IRA. Unlike a backdoor Roth IRA contribution (which involves non-deductible contributions), a conversion typically involves pre-tax money that has never been taxed.
The core trade-off is straightforward: you pay income tax on the converted amount today in exchange for tax-free growth and withdrawals in retirement. This can be a powerful strategy when your current tax rate is lower than the rate you expect to face later.
The single biggest factor in whether a Roth conversion makes sense is your current tax rate compared to your expected future tax rate. Converting when your rate is temporarily low locks in taxes at a discount.
1. Early Retirement (Ages 62-72)
The years after you stop working but before Social Security and required minimum distributions (RMDs) begin are often the lowest-income period of your life. Without a paycheck, your taxable income may drop significantly, creating a window to convert at the 10%, 12%, or 22% bracket instead of the 24%+ bracket you faced while working. RMDs start at age 73 (under current law), so the window between retirement and 73 is particularly valuable.
2. Job Transition or Sabbatical Year
A year between jobs, a sabbatical, or a year you start a business with low initial income can create a temporary low-bracket opportunity. If your income drops from $150,000 to $30,000, you have substantial room in the lower brackets to convert.
3. Year with Large Deductions
A year with unusually high deductions -- large medical expenses exceeding 7.5% of AGI, significant charitable contributions, or a large business loss -- can lower your taxable income enough to make a conversion attractive. The deductions offset some or all of the conversion income.
4. Market Downturn
When your IRA balance drops due to a market decline, converting the same number of shares generates less taxable income. If your IRA drops from $500,000 to $350,000, you can convert the same assets for $150,000 less in taxable income. When the market recovers, all that growth happens inside the Roth -- tax-free.
5. Before Tax Rates Increase
Many provisions of the 2017 Tax Cuts and Jobs Act (TCJA) are scheduled to expire after 2025. Under H.R. 1 (the "One Big Beautiful Bill Act"), these lower rates have been extended. However, future legislative changes could raise rates. Converting while rates are known and relatively low can hedge against this uncertainty.
i Pro Tip:
Many financial planners recommend converting early in the year. This gives you more time to assess your total annual income and make adjustments. If you convert in January and your income turns out higher than expected, you cannot undo the conversion -- but you can avoid additional conversions later in the year.
How to Calculate the Tax Impact of a Roth Conversion
The converted amount is added directly to your ordinary income for the year. Your tax depends on your filing status, existing income, and the size of the conversion.
Step-by-Step Tax Calculation
Start with your existing taxable income (wages, Social Security, pensions, investment income minus deductions)
Add the conversion amount to that income
Apply the 2026 federal tax brackets to the combined total
Subtract the tax you would owe without the conversion -- the difference is your conversion tax cost
2026 Federal Tax Brackets (Single Filers)
Taxable Income
Rate
Tax on Bracket
$0 - $11,925
10%
$1,193
$11,926 - $48,475
12%
$4,386
$48,476 - $103,350
22%
$12,073
$103,351 - $197,300
24%
$22,548
$197,301 - $250,525
32%
$17,032
$250,526 - $626,350
35%
$131,539
$626,351+
37%
Varies
Source: IRS Revenue Procedure 2024-40, as adjusted for 2026.
Example: Conversion During Early Retirement
Scenario: Single filer, age 63, retired
Other taxable income: $25,000 (pension)
Standard deduction: $15,000 (single) + $2,000 (age 65+) = $17,000
Taxable income before conversion: $8,000
Room before 22% bracket starts: $48,475 - $8,000 = $40,475
Optimal conversion: Convert $40,475 to stay within the 12% bracket.
Tax cost: 10% on first $3,925 ($393) + 12% on remaining $36,550 ($4,386) = approximately $4,779
Effective rate on conversion: approximately 11.8% -- far below the 24% or higher bracket this person may face when RMDs begin at 73.
Use our Roth Conversion Calculator to model your specific scenario with your actual income, deductions, and conversion amount.
Partial Conversions: The Tax Bracket Management Strategy
You do not have to convert your entire Traditional IRA at once. In fact, spreading conversions across multiple years is often the most tax-efficient approach. This strategy, sometimes called "bracket filling" or "bracket topping," involves converting just enough each year to use up the room in your current bracket.
How Bracket Filling Works
Year
Other Income
Bracket Space (22%)
Conversion Amount
Tax on Conversion
Running IRA Balance
Year 1
$50,000
$56,950
$56,950
$12,529
$443,050
Year 2
$50,000
$56,950
$56,950
$12,529
$386,100
Year 3
$50,000
$56,950
$56,950
$12,529
$329,150
Year 4
$50,000
$56,950
$56,950
$12,529
$272,200
Total converted over 4 years
$227,800
$50,116
--
Example assumes MFJ with $30,000 standard deduction and $50,000 other income, filling the 22% bracket. Actual brackets use 2026 MFJ thresholds ($96,951 - $206,700 at 22%). Bracket space = $206,700 - ($50,000 - $30,000 deduction) = approximately $186,700, simplified here for illustration.
Compare this to converting $227,800 all at once: a single-year conversion would push you into the 24% and potentially 32% bracket, costing significantly more in taxes. By spreading it over four years, you keep the effective rate on every converted dollar at 22% or below.
i Growth Note:
While you spread conversions over multiple years, the unconverted balance continues growing in your Traditional IRA. That growth is still pre-tax and will be taxable when eventually converted or distributed. If you expect strong market growth, converting sooner (even at a slightly higher bracket) may save more than waiting, because the growth happens tax-free in the Roth instead.
The Pro-Rata Rule for Roth Conversions
If your Traditional IRA contains both pre-tax and after-tax (non-deductible) contributions, you cannot choose to convert only the after-tax portion. The IRS applies the pro-rata rule, treating all your Traditional IRA accounts as a single pool.
How the Pro-Rata Rule Applies to Conversions
The formula determines what percentage of your conversion is taxable:
Pro-Rata Calculation
Taxable portion = (Total pre-tax IRA balance / Total IRA balance) x Conversion amount
The IRS uses your IRA balances as of December 31 of the conversion year, including all Traditional, SEP, and SIMPLE IRAs.
Even though you had $20,000 in after-tax contributions, only $5,000 of the conversion is tax-free. The remaining $45,000 is taxed as ordinary income.
How to Minimize Pro-Rata Impact
Roll pre-tax IRAs into your 401(k) -- employer plans are excluded from the pro-rata calculation. This is the most common and effective solution.
Convert the entire balance -- if the amount is manageable, converting everything eliminates the pro-rata issue for future years.
Avoid non-deductible contributions if you have large pre-tax IRA balances, as the mix complicates every future conversion.
For a detailed walkthrough of the pro-rata rule with the backdoor Roth strategy specifically, see our Backdoor Roth IRA Guide.
The 5-Year Rule for Roth Conversions
Roth IRAs have two separate 5-year rules that affect conversions. Understanding both is essential to avoid early withdrawal penalties.
Rule 1: The 5-Year Rule on Converted Amounts
If you are under age 59-1/2, each Roth conversion has its own 5-year holding period. Withdrawing converted amounts before 5 years triggers a 10% early withdrawal penalty on the converted amount (you already paid income tax on it, so you do not owe tax again -- just the penalty).
The 5-year clock starts on January 1 of the conversion year, regardless of when during the year you converted
A December 2026 conversion satisfies the rule on January 1, 2031
After age 59-1/2, this rule no longer applies -- you can withdraw converted amounts immediately without penalty
Rule 2: The 5-Year Rule on Roth Earnings
Separately, your Roth IRA must be open for at least 5 years before earnings can be withdrawn tax-free (even after age 59-1/2). This clock starts with your first Roth IRA contribution or conversion, whichever is earlier, and applies to the account overall -- not per conversion.
! Important:
If you are over 59-1/2 and already have a Roth IRA that has been open for 5+ years, neither 5-year rule is a practical concern for new conversions. This makes Roth conversions particularly straightforward for people in their 60s who established a Roth IRA earlier in life.
State Tax Considerations for Roth Conversions
Federal taxes are not the only cost of a Roth conversion. Most states tax Roth conversions as ordinary income, which can add 3% to 13% on top of federal taxes.
State-Specific Strategies
No-income-tax states -- If you live in a state with no income tax (Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington, Wyoming), you avoid state tax on conversions entirely. Some retirees move to a no-tax state before converting.
States that exempt retirement income -- Several states partially or fully exempt pension and retirement income from state taxes, which may include Roth conversion income. Check your state's specific rules.
States with flat rates -- States like Illinois (4.95%) and Pennsylvania (3.07%) have flat income tax rates, so conversions do not push you into higher state brackets.
States with progressive rates -- In states like California (up to 13.3%) or New York (up to 10.9%), large conversions can be especially costly. Partial conversions over multiple years are even more important in high-tax states.
i Relocation Strategy:
If you plan to relocate to a lower-tax state in retirement, consider delaying conversions until after the move. A $200,000 conversion in California could cost $20,000+ in state taxes that would be $0 in Florida. However, do not let state taxes alone drive the decision -- federal bracket management is typically the larger factor.
How Roth Conversions Affect Medicare Premiums and Other Benefits
A Roth conversion increases your modified adjusted gross income (MAGI), which can trigger consequences beyond income tax.
Medicare IRMAA Surcharges
Medicare Part B and Part D premiums are income-tested using your MAGI from two years prior. In 2026, Income-Related Monthly Adjustment Amount (IRMAA) surcharges apply at these thresholds:
MAGI (Single)
MAGI (MFJ)
Monthly Part B Surcharge
$106,000 or less
$212,000 or less
$0 (standard premium)
$106,001 - $133,000
$212,001 - $266,000
+$70.00/month
$133,001 - $167,000
$266,001 - $334,000
+$175.00/month
$167,001 - $200,000
$334,001 - $400,000
+$280.00/month
$200,001 - $500,000
$400,001 - $750,000
+$384.90/month
Above $500,000
Above $750,000
+$419.30/month
Source: CMS Medicare Part B premiums, 2026 thresholds (approximate -- final amounts announced each fall).
A large conversion in one year could push you into a higher IRMAA bracket two years later, adding $840 to $5,032 per person per year in additional premiums. Size your conversions to avoid IRMAA cliff effects when possible.
Other Income-Dependent Impacts
Social Security taxation -- Conversion income increases your "combined income," which can cause up to 85% of your Social Security benefits to become taxable. Use our Social Security Calculator to see how additional income affects benefit taxation.
Net Investment Income Tax -- If conversion income pushes your MAGI above $200,000 (single) or $250,000 (MFJ), you may owe the 3.8% Net Investment Income Tax on investment income (though not on the conversion itself).
ACA premium subsidies -- If you receive Affordable Care Act marketplace subsidies, conversion income increases your MAGI and can reduce or eliminate your premium tax credit.
Reducing Future RMDs Through Roth Conversions
One of the most compelling reasons to convert is to reduce or eliminate required minimum distributions. Roth IRAs have no RMDs during the account holder's lifetime, while Traditional IRAs require distributions starting at age 73.
Why RMD Reduction Matters
RMDs are calculated based on your Traditional IRA balance divided by a life expectancy factor. As your balance grows, so do your required withdrawals -- and the taxes on them. A $500,000 Traditional IRA at age 73 requires an RMD of approximately $18,868 (using the Uniform Lifetime Table divisor of 26.5). By age 80, the same account (assuming 5% growth) could require an RMD exceeding $30,000.
Every dollar you convert to a Roth before age 73 is a dollar that will not generate forced taxable income later. For a deeper look at RMD planning, see our RMD Rules 2026 guide and use the RMD Calculator to estimate your future required distributions.
Case Study: Converting Before RMDs Begin
Retiree age 63, Traditional IRA balance: $500,000
Pension income: $30,000/year
Plan: Convert $50,000/year for 10 years (ages 63-72)
Result: By age 73, the Traditional IRA is significantly reduced, and the Roth IRA holds a substantial balance growing tax-free. RMDs at 73 are based on a much smaller Traditional IRA balance, keeping total taxable income lower and potentially preserving a lower tax bracket throughout retirement.
Converting a large amount can push you into a much higher tax bracket, trigger IRMAA surcharges, and make Social Security benefits more taxable. Calculate the full income impact -- not just the marginal rate -- before choosing a conversion amount.
2. Paying the Tax from Converted Funds
If you withdraw part of the conversion to pay taxes, the withdrawn amount does not go into the Roth and may be subject to the 10% early withdrawal penalty if you are under 59-1/2. Pay the tax from separate funds (checking, savings, or taxable brokerage accounts) to maximize the amount that lands in the Roth.
3. Ignoring State Taxes
Federal taxes are only part of the cost. In states like California, Oregon, or Minnesota, state income taxes can add 8-13% to your conversion cost. Factor in state taxes when sizing your conversion.
4. Forgetting the IRMAA Two-Year Lookback
A conversion in 2026 affects your Medicare premiums in 2028. If you are approaching age 63-64, large conversions now may increase your premiums when you first enroll in Medicare at 65.
5. Not Considering the Pro-Rata Rule
If you have mixed pre-tax and after-tax IRA balances, assuming you can convert just the after-tax portion is a costly mistake. Review the pro-rata rule section before converting.
Frequently Asked Questions
How much tax will I pay on a Roth conversion?
The converted amount is added to your ordinary income for the year, and you pay your marginal tax rate on it. For example, if you are in the 24% bracket and convert $50,000, you would owe approximately $12,000 in additional federal income tax. The exact amount depends on your total taxable income and filing status. Use a Roth conversion calculator to model the tax impact before converting.
Can I convert only part of my Traditional IRA to Roth?
Yes, partial Roth conversions are allowed and are often the smartest tax strategy. You can convert any amount you choose each year. Many people convert just enough to fill up their current tax bracket without pushing into a higher one. There is no limit on the number of conversions per year.
What is the 5-year rule for Roth conversions?
Each Roth conversion has its own 5-year holding period before the converted amount can be withdrawn penalty-free (if you are under age 59-1/2). The clock starts on January 1 of the year you convert. After age 59-1/2, the 5-year rule on converted amounts no longer applies. For full details, see our 5-year rule section above.
When is the best time to do a Roth conversion?
The best time is generally when your income is temporarily lower than usual -- early retirement, a job transition, or a year with large deductions. Converting before RMDs begin (age 73) is especially valuable, as it reduces forced taxable income later. A market downturn can also be a good time, as the same assets generate less taxable income.
Does a Roth conversion affect my Medicare premiums?
Yes. Conversion income increases your MAGI, which can trigger IRMAA surcharges on Medicare Part B and Part D premiums. The surcharge is based on income from two years prior. In 2026, single filers with MAGI above $106,000 and joint filers above $212,000 pay higher premiums. Carefully size your conversion to avoid crossing IRMAA thresholds.
Can I undo a Roth conversion?
No. Since the Tax Cuts and Jobs Act of 2017 (effective for tax years 2018 and later), Roth conversions are irrevocable. You cannot recharacterize a conversion back to a Traditional IRA. This makes careful planning essential -- calculate the full tax impact before converting, as you will owe income tax on the converted amount regardless of what happens in the market afterward.
Model Your Roth Conversion Tax Impact
See exactly how much tax you would owe on a Roth conversion at different amounts. Compare scenarios and find the optimal conversion size for your situation.