By the FigureNerd team · Last reviewed: · Methodology
Roth Conversion Ladder NIIT CalculatorNavigate all three retirement tax cliffs at once
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.
Multi-year schedule
NIIT threshold tracking
IRMAA cliff detection
RMD do-nothing comparison
Converting too little from your traditional IRA each year means large required distributions later, at higher rates. Converting too much means a Medicare surcharge or NIIT you did not plan for. This calculator finds the Goldilocks number -- the conversion sweet spot that drains your account efficiently without stepping on any of the three cliffs.
Roth Conversion Ladder NIIT Calculator
Enter your numbers. The calculator builds your year-by-year conversion schedule automatically.
Reviewed by the FigureNerd retirement team. Thresholds sourced from IRS.gov, IRC Section 86, Section 408A, Section 1411, and CMS IRMAA announcements. Methodology
Your IRA and age
Your age now. Model runs from today through the modeled window.
When you plan to stop working (or reduce income significantly) -- start of the low-income conversion window.
Total across all traditional IRA and rollover IRA accounts. Do not include 401k unless planning to roll to IRA first.
Expected return inside the IRA. Models how fast the untouched balance grows and how RMDs escalate over time.
Income and Social Security
Drives NIIT threshold, IRMAA thresholds, and tax bracket breakpoints.
Married Filing Separately significantly reduces the NIIT threshold to $125,000 and limits Roth conversion room. Consult a CPA about your filing status strategy before proceeding.
Include wages, pension, rental income, dividends -- anything outside your traditional IRA. Exclude Social Security (entered below).
Once SS starts, its taxable portion reduces your Roth conversion room.
Annual benefit at your FRA. Pull from your SSA.gov statement. We estimate the taxable portion using IRC Section 86.
Target ceiling and model length
NIIT threshold: $250,000 MFJ / $200,000 Single (not indexed for inflation, IRC Section 1411). [CALEB-VERIFIED -- confirm annually]
IRMAA 2-year lookback: IRMAA Medicare surcharges are based on your MAGI from 2 years prior. Conversions you make today will affect your Medicare premiums 2 years from now. This calculator shows the IRMAA impact in the year it will be felt, not the year of conversion.
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.
Total Converted
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over model window
Tax on Conversions
--
estimated federal only
Est. Tax Saved vs Do-Nothing
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vs RMD path to age 90
Yr
Age
IRA Balance
Other Income
Max Conversion
MAGI After
NIIT
IRMAA
Tax on Conv.
Proj. RMD
Annual Conversion vs NIIT/IRMAA Cliffs
Stacked: other income (bottom) + conversion amount (top). Reference lines show the NIIT threshold and IRMAA Tier 1 ceiling for your filing status.
IRA Balance: Conversion Ladder vs Do-Nothing
Ladder path drains the account before RMD age. Do-nothing path continues growing, generating larger forced distributions at age 73 or 75.
If You Don't Convert (Do-Nothing Baseline)
IRA balance at RMD start age--
Year 1 RMD (approximate)--
Est. federal tax on Year 1 RMD--
Proj. total RMD tax burden (ages 73-90)--
Conversion total tax paid--
Estimated tax savings from converting--
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.
Roth Conversion 5-Year Rule Tracker
Each Roth conversion starts a new 5-year clock before that converted amount can be withdrawn tax-free. For account holders already over age 59.5 at time of conversion, the 10% early withdrawal penalty does not apply -- but a separate 5-year rule governs when Roth earnings become tax-free. [CALEB-VERIFY: Treas. Reg. 1.408A-6]
Year
Age at Conversion
Amount Converted
Available Penalty-Free From
Over 59.5?
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Open a self-directed Roth IRA and convert into real estate, private lending, and alternatives.
Directed IRA lets you convert traditional IRA dollars into tax-free Roth growth on investments you actually understand -- not just stocks and bonds.
Affiliate disclosure: FigureNerd may earn a commission if you use this link. No cost to you.
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.
Cliff 1: NIIT (3.8% on net investment income)
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.
Cliff 3: RMD acceleration risk
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.
The Goldilocks problem: convert too little and RMDs drive you into higher brackets at 73 or 75. Convert too much and you trigger NIIT, IRMAA, or both. The sweet spot is the largest annual conversion that keeps your MAGI just below the binding cliff for your situation.
Social Security inclusion and MAGI (IRC Section 86)
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.
The do-nothing baseline: why it matters
If your IRA is $850,000 today at age 62 and grows at 6% for 11 years, you arrive at RMD age with approximately $1.6 million. Your first RMD at 73 is roughly $60,000 -- on top of whatever other income you have. That $60,000 is taxable at ordinary rates, and the amount grows every year. The Roth conversion path drains the account at controlled rates during low-income years, potentially saving hundreds of thousands in lifetime federal tax.
Key flags and limitations
Inherited IRAs cannot be converted. Model only your own traditional IRA balance.
401k balances require a rollover first. Roll prior-employer 401k to a traditional IRA before starting this strategy.
State income tax is not modeled. Add your state rate to the federal cost for the full picture.
No income limit for Roth conversions. The income limits apply only to direct Roth IRA contributions, not conversions.
Qualified Charitable Distributions (QCDs) allow up to the indexed annual limit from a traditional IRA to charity, satisfying RMDs without adding to MAGI. [CALEB-VERIFY: 2026 QCD limit]
Married Filing Separately has a $125,000 NIIT threshold -- consult a CPA before executing any conversion strategy under this filing status.
The complexity of this strategy is exactly why a fee-only advisor earns their fee.
A fee-only financial planner can build a year-by-year Roth conversion schedule that accounts for your spouse's benefits, state taxes, estate planning goals, and full retirement income picture. Wealthtender matches you with vetted fee-only advisors.
Affiliate disclosure: FigureNerd may earn a commission if you use this link. No cost to you.
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.
Does a Roth conversion trigger NIIT?
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.
What is IRMAA and how does it affect Roth conversions?
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.
Is there an income limit for Roth conversions?
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.
What is the 5-year rule for Roth conversions?
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.
When do RMDs start?
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. [CALEB-VERIFY: IRS SECURE 2.0 guidance]
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.