Plan the right amount to convert from a traditional IRA to Roth each year, filling your tax bracket without triggering IRMAA cliffs or the 3.8% NIIT surcharge.
Default scenario: age 62, MFJ, $850K IRA at 6%, $55K/yr other income, SS starts at 67, target below NIIT threshold $250K, 10-year model.
| Yr | Age | IRA Balance | Other Income | Max Conversion | MAGI After | NIIT | IRMAA | Tax on Conv. | Proj. RMD |
|---|
Simplified projection using constant growth rate, 24% bracket on RMDs, and IRS Uniform Lifetime Table distribution periods. Individual results vary. Federal income tax only. Your state may also tax Roth conversions as ordinary income.
| Year | Age at Conversion | Amount Converted | Available Penalty-Free From | Over 59.5? |
|---|
Most Roth conversion calculators ask one question: how much should you convert this year? This calculator answers a harder question: how much should you convert each year for the next 5 to 20 years, accounting for your IRA's growth, Social Security inclusion, IRMAA's two-year lookback, and the RMD timetable that depends on what you have left at age 73 or 75.
The Net Investment Income Tax under IRC Section 1411 adds 3.8% to net investment income (dividends, capital gains, rental income) when your MAGI exceeds $200,000 (Single) or $250,000 (MFJ). A Roth conversion is ordinary income (not NII), but it raises your MAGI. If your MAGI crosses the threshold, your NII gets the surcharge. The threshold is not indexed for inflation and has been fixed since 2013.
IRMAA adds a monthly surcharge to Medicare Part B and Part D premiums when MAGI exceeds certain levels. Because IRMAA is based on MAGI from 2 years prior, a high-income conversion at 63 raises your Medicare premiums at 65. This calculator models IRMAA impact in the year it is felt so you can plan conversions around it.
Required Minimum Distributions begin at age 73 for those born 1951-1959, and age 75 for those born 1960 or later (SECURE 2.0). RMDs are a percentage of your account balance, so a larger balance means larger forced distributions at potentially higher rates. If you do not convert enough before RMD age, the IRS will force the distributions for you, at the rate of your choosing.
Social Security benefits enter MAGI through the combined income formula. Combined income = AGI (excluding SS) + non-taxable interest + half of SS benefit. Below $25,000 Single / $32,000 MFJ: 0% of SS in MAGI. Between the thresholds: up to 50%. Above $34,000 Single / $44,000 MFJ: up to 85%. These thresholds are not indexed for inflation: they have been fixed since 1994, so more SS is taxable every year as incomes rise.
If your IRA is $850,000 today at age 62 and grows at 6%, your RMD start age depends on your birth year, not a flat rule. Someone age 62 in 2026 was born in 1964, which falls in the "1960 or later" bucket, so RMDs start at 75, not 73. Run that forward 13 years at 6% and the account reaches approximately $1.81 million by the time RMDs begin. The first-year RMD, using the IRS Uniform Lifetime Table divisor of 26.5 at age 75, is approximately $73,700, on top of whatever other income exists that year. That amount is taxable at ordinary rates and grows every year after, since the divisor shrinks faster than the balance does in most scenarios. The Roth conversion path drains the account at controlled rates during low-income years instead, potentially saving hundreds of thousands in lifetime federal tax.
The default inputs (age 62, MFJ, $850,000 IRA at 6% growth, $55,000/yr other income, Social Security starting at 67 with a $28,000 FRA benefit, ceiling set to the NIIT threshold, 10-year model) produce a specific year-by-year pattern worth walking through, because it shows exactly how the "Goldilocks number" moves as Social Security phases in.
Year 1 (age 62): other income is $55,000 and Social Security has not started, so the full $195,000 gap to the $250,000 NIIT ceiling is available to convert. MAGI lands at exactly $250,000 (the ceiling, by design). Tax on that conversion, layered on top of $55,000 of other income in the MFJ bracket structure, comes to approximately $39,949, an effective rate of about 20.5% on the converted dollars. The $850,000 balance grows to $901,000 before the conversion, then drops to $706,000 after it.
Year 6 (age 67): Social Security starts. At $28,000/yr FRA benefit claimed exactly at full retirement age, the benefit is not reduced or increased: $28,000 flows in at full value. Under the IRC Section 86 combined-income formula, $55,000 of other income plus half of that $28,000 SS benefit puts combined income well above the $44,000 MFJ threshold, so 85% of the benefit ($23,800) becomes taxable and stacks onto MAGI. Total non-conversion income rises to $78,800, which shrinks the room left under the $250,000 ceiling to $171,200. This is the mechanism that makes late-arriving Social Security quietly erode conversion room in every ladder plan that ignores it.
Year 10 (age 71, end of the 10-year model): the $850,000 starting balance is fully converted: the live tool shows a $0 remaining IRA balance and correspondingly $0 further conversion, tax, or NIIT/IRMAA exposure for that year, even though $171,200 of ceiling room remains unused. That unused room is a sign the account was fully drained ahead of schedule under these assumptions; a real plan could shorten the model window or raise the ceiling in later years to leave less value un-optimized.
Total across the 10-year default run: $1.0 million converted, approximately $207,000 in federal tax on the conversions, versus a do-nothing path that owes an estimated $422,701 in RMD-era federal tax through age 90. That is an estimated $215,796 in lifetime federal tax saved by converting on a schedule instead of waiting for forced distributions (all four figures read directly from this page's own calculator, not assumed).
Every number on this page comes from the calculator's own live logic. As of the 2026-08-29 verification pass, the IRMAA tiers and the RMD distribution-period table below both match their primary sources exactly; two built-in simplifications remain worth knowing about before treating any output as a plan.
The do-nothing comparison taxes every dollar of projected RMDs at a flat 24%, disclosed in the small print under that panel. Real federal tax does not work that way: the first dollars of a large RMD fill whatever bracket space is left below 24%, but once combined income is large enough, later dollars spill into the 32% and 35% brackets. For a modest RMD stacked on modest other income, 24% is a reasonable flat approximation. For a much larger IRA balance that produces six-figure RMDs on top of pension or investment income, the flat-24% estimate will understate the true RMD-era tax bill, which makes the calculated "tax saved from converting" figure conservative in exactly the cases where converting matters most.
The early/delayed claiming adjustment in this tool assumes a full retirement age of 67, which is correct only for people born in 1960 or later. Full retirement age was 66 for people born 1943-1954, and phased up to 67 in two-month steps for people born 1955-1959. If you were born before 1960 and plan to claim Social Security before or after your actual FRA, the reduction or delayed-credit percentage this tool computes will be off by a small amount. Confirm your exact FRA and benefit estimate directly from your SSA.gov account statement before finalizing a ladder around a specific claiming age.
A multi-year strategy of converting portions of a traditional IRA to Roth each year during the low-income window between retirement and RMD start age. The goal is to pay tax at lower rates now, rather than higher rates on forced RMDs later.
The conversion amount is ordinary income, not net investment income. But it raises your MAGI. If your MAGI after conversion exceeds $250,000 (MFJ) or $200,000 (Single), investment income you have that year is subject to the 3.8% NIIT surcharge.
IRMAA is a Medicare premium surcharge based on MAGI from 2 years prior. A large Roth conversion today will raise Medicare Part B and Part D premiums 2 years from now. Planning conversions below the IRMAA Tier 1 threshold is a core goal of the conversion ladder strategy.
No. There is no income limit for converting a traditional IRA to Roth. The income limits in the tax code apply only to direct Roth IRA contributions.
Each Roth conversion starts a separate 5-year clock. If you are under 59.5 at conversion, you must wait 5 years before withdrawing converted amounts without the 10% early withdrawal penalty. If you are over 59.5 at conversion, the penalty does not apply to converted amounts, though a separate 5-year rule governs when Roth earnings become tax-free.
Under SECURE 2.0, RMDs begin at age 73 for those born 1951-1959, and age 75 for those born 1960 or later. Roth IRAs have no RMDs during the owner's lifetime. Confirmed against the IRS's own Retirement topics: Required Minimum Distributions page.
Per the CMS 2026 Medicare Parts B Premiums and Deductibles fact sheet, the 2026 IRMAA Tier 1 threshold for married filing jointly is $218,000 of MAGI, based on 2024 income (the 2-year lookback). This calculator's built-in reference line matches that figure exactly, and remember the 2-year lookback means your 2026 premium is set by 2024 income.
No. Every dollar figure on this page (the tax on conversions, the do-nothing RMD tax estimate, and the total savings) is federal only. States that tax retirement income as ordinary income (most states with an income tax) will add their own rate on top of every number shown here. States with no income tax, or that exempt retirement account withdrawals, will not change the after-tax picture at all. Check your specific state's treatment of Roth conversions and traditional IRA distributions before finalizing a multi-year plan.
The calculator caps the conversion at whichever is smaller: the room left under your target ceiling, or the remaining IRA balance. In the default 10-year model, the $850,000 starting balance is fully converted by year 10, so the model shows $0 conversion, $0 tax, and $0 remaining balance for any year after the account is drained, even though ceiling room is still available. That is the tool correctly recognizing there is nothing left to convert, not an error.
Disclaimer. This calculator is designed to model Roth conversion planning scenarios. It uses simplified tax bracket modeling, assumes constant annual returns, and applies the most recently confirmed NIIT and IRMAA thresholds. Actual results will vary based on market returns, tax law changes, your specific Social Security inclusion calculation, and state income tax treatment of conversions. This calculator does not provide tax advice. Work with a fee-only financial advisor or CPA who specializes in retirement tax planning before executing a Roth conversion strategy. See our Terms for the full disclaimer.
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