Roth Conversion Calculator

Analyze the benefits of converting traditional IRA funds to Roth, considering current vs future tax brackets, RMDs, and Medicare IRMAA thresholds

How this tool works

Enter your account balances, income, tax assumptions, and conversion amount. The calculator compares the tax you pay today with modeled future taxes, RMDs, and Medicare IRMAA effects. Use the result to compare a few possible conversion paths—not as a tax filing or personal recommendation.

Understanding Roth Conversions

Converting traditional IRA funds to a Roth IRA means paying taxes now on the converted amount, but all future growth and withdrawals will be tax-free. This calculator helps you analyze whether converting makes sense by comparing the tax cost today versus the tax savings in retirement, while considering Required Minimum Distributions (RMDs), Medicare IRMAA surcharges (2-year lookback), the 3.8% Net Investment Income Tax (NIIT), and the opportunity cost of paying taxes early (discount rate).

Personal Information

Current Age

Retirement Age (leave blank if already retired) Leave blank if you're already retired

Life Expectancy

Filing Status

Financial Situation

Traditional IRA/401(k) Balance ($) Current balance in traditional retirement accounts

Current Roth IRA Balance ($) Current balance in Roth accounts

Legacy Current Income ($) Used only by older saved scenarios. Enter current income by source below.

Other Annual Ordinary Income ($) Pensions, wages, or other taxable ordinary income. Exclude Social Security and retirement withdrawals.

Social Security and Taxable Brokerage

Your Annual Social Security ($)Gross annual benefit before Medicare deductions.

Spouse Annual Social Security ($)After a modeled death, the survivor receives the higher benefit, not both.

Taxable Brokerage Balance ($)Non-retirement investments available for spending or conversion taxes.

Taxable Brokerage Cost Basis ($)Used to estimate capital gains when brokerage assets are sold.

Annual Taxable Interest/Ordinary Dividends ($)

Annual Qualified Dividends/Long-Term Gains ($)

Spending from your portfolio (optional)

Annual Portfolio Withdrawal (%) Percent of your total portfolio (Traditional + Roth) you plan to withdraw each year for spending. Traditional withdrawals are taxable; Roth is tax‑free. RMDs still happen separately.

Withdrawal Mode If you choose “target after‑tax,” the calculator will increase withdrawals as needed to cover conversion/RMD taxes while maintaining your spending target.

Withdrawal Order Traditional withdrawals are taxed as income; Roth withdrawals are tax‑free.

Target Ordinary Tax Bracket (%)For the bracket-aware withdrawal order.

Conversion and Income Tax Payment Source

Survivor / Widow Scenario

Assumed Your Death Age (0 = none)The model files jointly in the year of death and switches the spouse to single the following year.

Spouse Life Expectancy

Survivor Spending (% of Joint)

Other Income Continuing to Survivor (%)

Conversion Strategy

Annual Conversion Amount ($) Amount to convert each year

Number of Years to Convert How many years to spread conversions

Medicare IRMAA

Include Medicare IRMAA surcharges Adds Part B & Part D income-related premium surcharges to all-in tax cost. Uses a 2-year income lookback (same as Social Security / Medicare).

Medicare Enrollment Age Age when you (and spouse, if married) enroll in Medicare Part B. IRMAA applies once enrolled.

Annual Tax-Exempt Interest ($) Municipal bond interest (Form 1040 line 2a). Added to gross income for MAGI / IRMAA thresholds.

Net Investment Income Tax (NIIT)

Include NIIT (3.8% surtax) Applies when MAGI exceeds $200k (single/HOH), $250k (MFJ), or $125k (MFS). Tax is 3.8% on the lesser of net investment income or MAGI above the threshold.

NIIT uses the taxable interest, dividends, capital gains, and gains recognized on brokerage sales entered above.

Assumptions

Expected Annual Investment Return (%) Expected portfolio growth rate

Taxable Brokerage Return (%)

Expected Annual Inflation Rate (%) For adjusting brackets over time

Tax Discount Rate (%) — Optional Opportunity cost of paying taxes now vs. later. Tax dollars paid today could stay invested (e.g., in an index fund). A higher rate makes future tax savings worth less in today’s dollars. Try 3–7% to match expected portfolio returns. Leave at 0 for nominal (undiscounted) totals only.

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