Roth Conversion Calculator: How Much to Convert Each Year

A Roth conversion moves money from a traditional IRA or 401(k) into a Roth IRA. You pay income tax on the converted amount this year, and in exchange the money grows tax-free, its earnings come out tax-free once you are 59½ and five years have passed since your first Roth IRA contribution or conversion, and it never counts toward a required minimum distribution (RMD). ¹ There is no income limit and no annual cap on conversions. The question is how much to convert, in which years, and at what tax rate.

The calculator below works through that for a retired household. It runs the same household to age 95 twice, with the same spending in both runs. One converts each year up to the top of a federal bracket you choose, until a stop age. The other never converts; it withdraws from its traditional accounts as spending requires and takes RMDs when they start. Conversion tax is paid from taxable savings while they last and withheld from the IRA after that. The calculator compares what each household has left after tax. Filling to a bracket top is a rule of thumb that the calculator tests; the best amount for a given year can fall inside a bracket, which is what its “tax on the next $1k” column helps you find.

What the calculator assumes

The flat heir rate is the largest simplification. A non-spouse heir empties an inherited IRA over ten years at their own rates, which depend on their income in those years. ¹ The calculator handles that uncertainty with its break-even column: the heir rate at which converting and not converting come out equal. If your heirs are likely to pay more than that, converting wins.

How a conversion is taxed

The pre-tax amount you convert is ordinary income in the year it leaves the traditional account, taxed at the same rates as wages or an RMD. After-tax basis in the IRA is not taxed again. ⁴ A conversion counts in the calendar year it happens, so the deadline is December 31; the April filing deadline that applies to IRA contributions does not apply. Since 2018 a conversion cannot be reversed, so a conversion made in January that looks expensive by December stays on that year’s return. ⁴

When converting pays: the break-even tax rate

If the tax rate is the same at conversion and at withdrawal, and the tax on the conversion comes out of the converted money, the Roth and the traditional account end with the same after-tax value. Vanguard states it directly: “When the marginal tax rate stays the same, the Roth and the traditional IRA will generate the same after-tax withdrawal values.” ⁵ The whole decision comes down to two questions: what rate do you pay now, and what rate would the same dollars face later?

Vanguard calls the future rate at which you would be indifferent the break-even tax rate, or BETR. When the conversion tax is paid from the IRA, the break-even rate equals today’s rate. Paying the tax from a taxable account lowers it, because it moves the tax money into the Roth too. In Vanguard’s example at a 35% current rate over 20 years, the break-even rate drops to 30.1% when the tax comes from a tax-efficient taxable portfolio, 23.5% from a tax-inefficient one, and 14.1% from cash. ⁵ McQuarrie and DiLellio reach the same conclusion: “It is optimal to pay the tax on a conversion from outside the converted funds.” ⁶

The calculator reports a related number: the tax rate your heirs would have to pay on the leftover pre-tax balance for converting and not converting to end equal. Above that rate, converting wins.

Where the low-rate years come from

Most retirees have a stretch of years with unusually little taxable income. Wages have stopped, Social Security may not have started, and RMDs begin only at 73 for people born from 1951 through 1959 and at 75 for people born in 1960 or later. ^{7, 8} In those years the standard deduction and the lower brackets sit partly or entirely empty.

For 2026, a married couple filing jointly pays 10% and 12% on taxable income up to $100,800, after a $32,200 standard deduction. Single filers reach the 22% bracket at $50,400, after a $16,100 deduction.⁹ A married couple under 65 with no other income could therefore convert $133,000 in 2026 and stay inside the 12% bracket, for $11,600 of federal tax: an average rate of 8.7%. From 65, an additional $1,650 per spouse and, through 2028, the $6,000 senior deduction per person widen that room. ^{10, 3}

Those empty brackets do not carry over. A year in which you convert nothing, and your taxable income is near zero, wastes that low-rate room for good. The same pre-tax dollars may later come out as RMDs on top of Social Security, at a higher rate.

What each bracket did for one modeled couple

The calculator opens on a married couple born in 1962, so 64 in 2026 and already retired. They have $1.5 million in pre-tax accounts, $400,000 in taxable savings, no pension, and $60,000 a year of Social Security from age 70. They spend $90,000 a year after tax, paid from Social Security first, then taxable savings, then IRA withdrawals. Every account earns a 4% real return, all figures are in today’s dollars, and their heirs pay 24% on whatever pre-tax balance is left at 95. Their RMDs start at 75.

Without conversions, they live on taxable savings from 64 to 67 with almost no taxable income, then on IRA withdrawals taxed at 10% and 12%. Their pre-tax balance reaches about $1.98 million at 75. The first RMD is $80,419, and from 77 on the RMDs keep them in the 22% bracket, with the largest RMD at $127,180. With conversions to the top of the 12% bracket, they convert $133,000 to $148,000 a year from 64 to 67, paying the $11,600 of tax from savings. Once savings run out at 68, they keep converting $35,000 to $54,000 a year to the same bracket top, with the tax withheld from the IRA, until 74. That is $873,000 converted in all. Their first RMD falls to $26,626, and every RMD stays in the 12% bracket.

Summitward calculator, default inputs: married, born 1962, $1.5M pre-tax and $400,000 taxable on December 31, 2025, $90,000 of after-tax spending, $60,000 of Social Security from 70, 4% real return, heirs taxed at 24%, 2026 federal rules held flat in today’s dollars, no state tax.

Filling the 22% bracket empties the IRA by 70. It pays 22% on dollars that would otherwise have come out later at 10% or 12%, and it crosses the first Medicare IRMAA threshold in all seven conversion years. Filling 24% pays a higher rate still. The 12% fill leaves $325,000 of pre-tax money at 95, a balance whose RMDs, about $40,000 a year at the end, stay in the 12% bracket.

Measured at 95, the 12% fill left $253,000 more, 9.3% more than not converting, after $104,000 of federal tax on the conversions. The horizon matters for the larger fills. If the last spouse died earlier, with heirs still taxed at 24%:

The 22% fill’s gain is largest with an early death, $109,000 at 80, because it moves the most money out of the pre-tax account before heirs would pay 24% on it. Its edge then erodes because the household that did not convert keeps drawing its pre-tax money out as RMDs taxed at 22% or less, below the 24% its heirs would have paid. The 12% fill came out ahead at every age.

We reran the comparison with one input changed at a time. Filling the 12% bracket came out ahead in every variation, and ahead of the larger fills.

After-tax wealth at 95 with conversions minus without. Same calculator and assumptions as above, one input changed per row (two for the smaller household).

The 22% fill paid off when the later tax rate was likely to be high: a $3 million balance, a pension, a survivor filing single on brackets half as wide, heirs at 32%, or a 6% real return that grows the RMDs. It lost when heirs paid nothing, returns were low or spending was high. The 24% fill lost in every row. Starting at 71 left two years before RMDs began, and the 12% fill’s gain shrank to $41,000. These are results for one household under fixed assumptions. A pension, a younger retirement, state tax or a different claiming age can change the order, which is what the calculator’s bracket table is for.

Costs the bracket rate leaves out

A conversion dollar can cost more than its bracket rate, because several other rules key off the same income.

Social Security taxation

Up to 85% of Social Security benefits become taxable as other income rises. The thresholds are $25,000 and $34,000 of provisional income for single filers and $32,000 and $44,000 for joint filers, and they are not indexed to inflation. ² Inside the range where benefits are being phased in at 85%, each extra dollar of IRA income adds $1.85 of taxable income. In the 12% bracket that is a 22.2% effective rate; in the 22% bracket it is 40.7%. Converting before Social Security starts avoids this range entirely, which is why claiming later and converting earlier work together. In Geisler and Hulse’s single-retiree case, adding $30,000 of Social Security from 66, along with RMDs, cut the gain from bracket filling from 7.17% more portfolio life to 1.58%; delaying the benefit restored much of it. ¹¹

Medicare IRMAA surcharges

Medicare Part B and Part D premiums rise in steps once modified adjusted gross income passes $109,000 for single filers or $218,000 for joint filers in 2026. The first step adds $81.20 a month to Part B and $14.50 to Part D, per person. ¹² Each tier is a cliff: one dollar over the line costs the full surcharge for the year. Premiums are set from the tax return two years earlier, so income at 63 sets the premium at 65. ¹³ A voluntary Roth conversion is not one of the life-changing events that allow an appeal. ¹⁴ The calculator’s IRMAA switch caps conversions at the first threshold from 63 on.

The senior deduction phase-out

For 2025 through 2028, taxpayers 65 and older get an extra $6,000 deduction each, reduced by 6% of modified AGI above $75,000 ($150,000 joint). ³ Inside that phase-out, each conversion dollar adds $1.06 of taxable income for one qualifying person and $1.12 when both spouses qualify.

ACA premium tax credits before 65

Retirees buying marketplace coverage before Medicare face the largest cliff. The enhanced credits expired after 2025, so in 2026 eligibility again stops at 400% of the federal poverty line, and any excess advance credit must be repaid in full. ^{15, 16} Conversion income counts toward that limit. A conversion that pushes household income one dollar past 400% can cost the entire year’s credit. The calculator does not model ACA credits; if you rely on them, plan conversions around the limit first.

The net investment income tax

Conversion income is not net investment income, but it raises the modified AGI that decides whether the 3.8% tax applies to your dividends, interest and capital gains. The thresholds, $200,000 single and $250,000 joint, are not indexed. ^{17, 18}

Pay the tax from outside the IRA

Paying the tax from taxable savings converts more money into the Roth for the same tax bill. Withholding the tax from the conversion itself shrinks the Roth, raises the break-even rate to today’s rate, and before 59½ the withheld amount counts as an early distribution.^{5, 1} How much paying from outside is worth depends on what the outside money would otherwise earn after tax. Vanguard’s break-even rates show the range: a small gain when it comes from a tax-efficient index portfolio, a large one when it comes from cash.⁵ If raising the cash means selling investments with large gains, the capital-gains tax is part of the conversion cost. ⁶

The calculator pays the tax from taxable savings while they last and withholds it from the IRA after that. Its tax drag setting is how much tax the taxable account pays each year on dividends and realized gains. At the default of zero, a taxable dollar and a Roth dollar are worth the same, so paying from outside earns no credit and the results lean against converting. Setting a 0.5% drag raised the modeled couple’s 12% result from $253,000 to $352,000, mostly because the household that did not convert reinvests its unspent RMDs, about $1.8 million by 95, in an account that pays the drag.

When to convert less, or not at all

• Your heirs or charities will pay a low rate. A charity pays no tax on an inherited IRA, and qualified charitable distributions (QCDs) let you give up to $111,000 a year from an IRA tax-free from age 70½. Money headed there gains little from converting. ^{1, 19} In our modeled couple, heirs at 0% turned the 22% fill into a $248,000 loss and cut the 12% fill’s gain from $253,000 to $83,000.
• You would pay the tax from the IRA. The break-even rate is then today’s rate, with no margin. ⁵
• You are on ACA credits and the conversion would cross 400% of the poverty line. ¹⁵
• You expect to move to a lower-tax state. Converting before a move from a high-tax state to one without an income tax pays state tax you could avoid. Some states exempt conversions outright; Illinois lets residents subtract IRA distributions, including amounts converted to a Roth. ²⁰
• Your balance is small enough that RMDs stay in a low bracket. A married couple at 75 with $50,000 of Social Security and no other income would need roughly $2.3 million of pre-tax savings before the RMD alone reached the 22% bracket, by our calculation from 2026 rules once the senior deduction ends after 2028. In the Federal Reserve’s 2022 Survey of Consumer Finances, 8.4% of households headed by someone 65 to 74 had $1 million or more in all retirement accounts combined. ²¹
• You need the money within five years and are under 59½. Each conversion has its own five-year clock.¹

The case for converting gets stronger with a large balance, a pension, heirs in their peak earning years, or a spouse likely to be widowed. A non-spouse heir has to empty an inherited IRA within ten years, and if you die after your RMDs begin, they must also take annual RMDs in the first nine. ^{1, 22} A survivor files single after the year of death (or two more years with a dependent child), with half the bracket width and lower Social Security thresholds. ²³

Studies of bracket-filling conversions

The academic work agrees on direction and finds modest gains. Cook, Meyer and Reichenstein found that converting enough each year to fill a low bracket, while spending from taxable savings, added about two to three years of portfolio longevity compared with the conventional withdrawal order in their examples. ^{24, 11} T. Rowe Price’s analysis called the gain from tax-efficient withdrawals “incremental, not life-changing,” and found conversions “sometimes beneficial, but not overwhelmingly so,” because at lower incomes the benefit “is largely negated by higher taxation of Social Security benefits.” The same paper notes conversions “may be more beneficial at higher income levels (e.g., reducing unneeded RMDs taxed at 24% via Roth conversions taxed at 12%).” ²⁵

McQuarrie and DiLellio found that “most Roth conversions will show a substantial payoff if the client’s planning horizon stretches over decades; however, shorter time frames may produce only a minimal payoff or even a loss.” They list converting in the low part of the 22% bracket, when RMDs will later be taxed at 12%, among the riskiest cases. ⁶ McQuarrie’s later present-value study calls conversions aimed at RMDs a risky bet with small upside, least risky at 12% or less. ²⁶ The modeled couple above matches that pattern.

Few people convert. In 2023, 1.6 million taxpayers converted $36.7 billion to Roth IRAs, about 2.2% of the 71 million taxpayers with IRAs. Taxpayers aged 60 to 74 were 31% of those who converted and moved 61% of the dollars.²⁷

The rules to get right

• Five-year clock. Each conversion starts its own five-year period on January 1 of the conversion year. Withdrawing the converted amount within it before 59½ triggers the 10% additional tax. ¹
• A second five-year clock for earnings. Roth earnings come out tax-free only in a qualified distribution: after 59½ (or disability or death) and after five years from the first year any Roth IRA was funded for you. That clock is separate from each conversion’s own clock. ¹
• Money still in a workplace plan. An in-plan Roth conversion is available only if your 401(k) or 403(b) offers it. Rolling the money out to convert in an IRA requires a distribution the plan allows, which usually means leaving the employer or reaching the plan’s in-service withdrawal age. ²⁸
• Pro-rata rule. If any of your traditional, SEP or SIMPLE IRAs hold after-tax basis, every conversion is part taxable and part tax-free in proportion to the total of all those IRAs on December 31. Form 8606 does the calculation. Balances in a 401(k) are not part of that total. ^{29, 30}
• RMD first. In an RMD year, the first dollars out count toward the RMD, and an RMD cannot be converted. Take the full RMD, then convert. ^{4, 31}
• No undo. Conversions made in 2018 or later cannot be recharacterized. ⁴
• Brackets have no scheduled end. The 2025 reconciliation law made the current individual rates permanent. Congress can still change them, which is a reason to compare against a range of future rates instead of one forecast. ³²

Frequently asked questions

How much should I convert to a Roth each year?

Start with the marginal rate: convert while the tax on the next $1,000 is lower than you expect those dollars to face later, for you, a survivor or your heirs. Paying the tax from savings that would otherwise be taxed each year lowers the break-even rate, so a slightly higher rate now can still pay off. ⁵ For the modeled couple above, the top of the 12% bracket did best, which for a married couple under 65 with no other income in 2026 means $133,000 of conversion. The calculator’s bracket table and next-$1k column show where to stop for your own inputs.

Is there a limit on how much I can convert?

No. There is no income limit and no annual cap. The limit is the tax rate you are willing to pay.

Should I fill the 22% or the 24% bracket?

When the full cost of converting at that rate is below what the money would cost later. The usual signs are large RMDs, a survivor likely to file single, or heirs in high brackets. A lower future rate does not rule it out on its own: in Vanguard’s 20-year example, converting at 35% broke even against a future rate of 30.1% when the tax came from a tax-efficient taxable portfolio. ⁵ For a married couple under 65, MAGI passes the first IRMAA threshold of $218,000 at about $185,800 of taxable income, inside the 22% bracket, so a full 22% fill from 63 on already adds Medicare surcharges two years later. ¹²

Do Roth conversions raise Medicare premiums?

They can. Conversion income counts toward the MAGI that sets IRMAA, with a two-year lag: a conversion at 63 sets premiums at 65. ¹³

Can I convert after RMDs start?

Yes, but only after taking that year’s full RMD, and the RMD itself cannot be converted. ⁴

Can I undo a Roth conversion?

No. Recharacterizing a conversion has not been allowed since 2018.⁴

Should I convert when the market is down?

The same tax buys more shares, and any recovery happens in the Roth. That helps only if you would have converted anyway; a lower price does not change whether today’s rate beats the future rate.

What is the deadline for a Roth conversion?

December 31. A conversion is income in the year it is made; the April deadline for IRA contributions does not apply. ⁴

Key takeaways

• Compare two rates. Converting pays when today’s rate is below the rate the same dollars would face later, for you, a survivor or your heirs.
• Pay the tax from outside the IRA. It lowers the break-even rate and moves more money into the Roth. ⁵
• Use the years before Social Security and RMDs. Empty low brackets in those years cannot be used later.
• Bigger fills can lose. For one modeled couple with $1.5 million pre-tax, filling 12% left $253,000 more at 95, filling 22% came out even, and filling 24% left $256,000 less. The 12% fill was ahead whether the last spouse died at 80 or 95.
• Watch the cliffs. Social Security taxation, IRMAA from 63, the senior deduction phase-out and the ACA 400% limit all raise the cost of a conversion dollar.

Related guides

• RMD Calculator: Your Required Minimum Distribution and What It Costs in Tax shows the tax rate your RMD dollars will face, the number to compare against.
• Roth Conversion Ladder: A Step-by-Step Strategy covers converting to reach retirement money before 59½.
• Roth vs. Traditional 401(k) and IRA: The Tax Math That Actually Matters is the same rate comparison made at contribution time.
• When to Claim Social Security: The Math Behind the Decision decides how many low-tax years you have to convert in.
• The ACA Subsidy Cliff Is Back: Health Insurance for Early Retirees in 2026 covers the income limit that matters most before 65.
• Tax-Aware Decumulation: A Guide for Self-Directed High Earners sequences withdrawals across brackets, NIIT, IRMAA and ACA credits.

Sources

1. Internal Revenue Service. Publication 590-B, Distributions from Individual Retirement Arrangements (IRAs), 2025 edition. irs.gov
2. Internal Revenue Service. Publication 915, Social Security and Equivalent Railroad Retirement Benefits, 2025 edition. irs.gov
3. Internal Revenue Service. “Check your eligibility for the new enhanced deduction for seniors.” 26 U.S.C. 151(d)(5)(C). irs.gov
4. Internal Revenue Service. Publication 590-A, Contributions to Individual Retirement Arrangements (IRAs), 2025 edition, “Converting From Any Traditional IRA Into a Roth IRA” and “Required distributions.” irs.gov
5. James M. Passman, Boris C. Wong and Joel M. Dickson. “A ‘BETR’ Approach to Roth Conversions.” Vanguard Research, July 2025. vanguard.com
6. Edward F. McQuarrie and James DiLellio. “The Arithmetic of Roth Conversions.” Journal of Financial Planning, May 2023. financialplanningassociation.org
7. 26 U.S.C. 401(a)(9)(C)(v), applicable age for required minimum distributions, as amended by SECURE 2.0 Act section 107. law.cornell.edu
8. Proposed regulations, “Required Minimum Distributions,” 89 Fed. Reg. 58644, July 19, 2024 (applicable age 73 for 1959 births). federalregister.gov
9. Internal Revenue Service. “IRS releases tax inflation adjustments for tax year 2026, including amendments from the One, Big, Beautiful Bill.” irs.gov
10. Internal Revenue Service. Revenue Procedure 2025-32, section 4.14(3), additional standard deduction for age 65 or older. irs.gov
11. Greg Geisler and David Hulse. “The Effects of Social Security Benefits and RMDs on Tax-Efficient Withdrawal Strategies.” Journal of Financial Planning 31(2), February 2018, 36-47. financialplanningassociation.org
12. Centers for Medicare & Medicaid Services. “2026 Medicare Parts A & B Premiums and Deductibles” fact sheet. cms.gov
13. Social Security Administration. POMS HI 01101.020, IRMAA sliding scale tables, and HI 01101.010, modified adjusted gross income. ssa.gov
14. Social Security Administration. POMS HI 01120.001, IRMAA life-changing events. ssa.gov
15. Internal Revenue Service. “Questions and answers on the premium tax credit.” irs.gov
16. KFF. “Midterm Election Update: The Affordable Care Act Marketplaces.” October 6, 2026. kff.org
17. 26 U.S.C. 1411(c)(5), net investment income tax. law.cornell.edu
18. Internal Revenue Service. “Questions and answers on the net investment income tax.” irs.gov
19. Internal Revenue Service. Notice 2025-67, 2026 limitations adjusted as provided in section 415(d). irs.gov
20. Illinois Department of Revenue. Publication 120, Retirement Income. tax.illinois.gov
21. Board of Governors of the Federal Reserve System. 2022 Survey of Consumer Finances, summary extract public data (variable RETQLIQ, weighted). Summitward calculation; includes IRA and workplace-plan balances, Roth included. federalreserve.gov
22. Treasury Decision 10001, “Required Minimum Distributions.” 89 Fed. Reg. 58886, July 19, 2024. federalregister.gov
23. Internal Revenue Service. Publication 501, Dependents, Standard Deduction, and Filing Information. irs.gov
24. Kirsten A. Cook, William Meyer and William Reichenstein. “Tax-Efficient Withdrawal Strategies.” Financial Analysts Journal 71(2), 2015, 16-29. doi.org
25. Roger Young. “How to Make Your Retirement Account Withdrawals Work Best for You.” T. Rowe Price, views as of February 2022, page 10 and Appendix 4. troweprice.com
26. Edward F. McQuarrie. “Net Present Value Analysis of Roth Conversions.” Journal of Financial Planning 37(9), September 2024. financialplanningassociation.org
27. Internal Revenue Service, Statistics of Income. “Accumulation and Distribution of Individual Retirement Arrangements,” tax year 2023, Tables 1 and 4. irs.gov
28. Internal Revenue Service. Notice 2013-74, in-plan Roth rollovers. irs.gov
29. 26 U.S.C. 408(d)(2), aggregation of individual retirement plans. law.cornell.edu
30. Internal Revenue Service. Instructions for Form 8606, Nondeductible IRAs. irs.gov
31. 26 CFR 1.408-8, required minimum distributions from IRAs. ecfr.gov
32. Congressional Research Service. R48611, “Tax Provisions in P.L. 119-21, the FY2025 Reconciliation Law,” section 70101. July 29, 2025. congress.gov

Editor’s note

Rules and figures were checked against IRS, CMS, SSA and Federal Register sources in October 2026. Calculator results use 2026 federal rules held flat in today’s dollars, assume both households spend the same amount, give the taxable account no tax drag unless you set one, and ignore state tax, ACA credits and capital gains. This guide is educational and is not tax advice; confirm a conversion plan with a tax professional before acting on it.