Roth Conversion Calculator 2026: Tax & IRMAA Impact
Figures last verified against official sources in July 2026.
Quick Answer
Converting a Traditional IRA to a Roth IRA creates taxable ordinary income in the year of conversion. In 2026, if a conversion pushes your MAGI above $106,000 (single) or $212,000 (joint), it triggers an extra Medicare IRMAA surcharge of $81.20 to $443.90 per month two years later.
Retirees considering a Roth conversion often calculate the income tax bill but forget about the "hidden tax" — triggering a higher Medicare IRMAA premium tier two years later. We built this calculator to give seniors a total cost picture (upfront tax + Medicare IRMAA impact + estimated break-even years) in seconds without needing an account.
- Retirees in their 60s looking to reduce future mandatory RMDs through strategic Roth conversions.
- Medicare beneficiaries wanting to make sure an IRA conversion does not trigger a surprise IRMAA surcharge.
- Adults doing tax bracket filling to optimize lifetime tax-free wealth transfer to heirs.
Roth Conversion Calculator 2026
Calculate your upfront tax bill and check if a Traditional-to-Roth IRA conversion triggers a Medicare IRMAA premium surcharge.
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How to Use This Calculator — Step by Step
- Enter the conversion amount. Enter the dollar amount of pre-tax Traditional IRA or 401(k) funds you plan to convert to a Roth IRA this tax year.
- Enter your current MAGI. Enter your estimated Modified Adjusted Gross Income before the conversion (Form 1040 Line 11 plus Line 2a tax-exempt interest).
- Select your marginal tax bracket & filing status. Choose your federal tax bracket (e.g. 12%, 22%, 24%) and filing status to compute the exact tax bill.
- Review your total cost & IRMAA alert. The calculator displays your federal tax owed, checks whether your new MAGI triggers an IRMAA surcharge, and estimates your break-even timeframe.
💡 Pro Tip
Always pay conversion taxes using taxable cash (savings/checking accounts) rather than withholding from the IRA itself. Withholding from the IRA reduces your tax-free growth and incurs a 10% penalty if under age 59½. Check IRS conversion rules at irs.gov/retirement-plans.
Why Multi-Year Partial Roth Conversions Work Best
Instead of converting a large Traditional IRA all at once in a single year — which pushes you into a high marginal tax bracket and triggers maximum IRMAA surcharges — financial planners recommend multi-year partial conversions.
By converting smaller amounts each year between retirement and age 73 (when mandatory RMDs begin), you fill up the lower 12% or 22% tax brackets without pushing your MAGI over the $106,000 single / $212,000 joint IRMAA cliff.
Real-Life Examples — Roth Conversion Planning
Donald, 64 — Partial Conversion Staying Under IRMAA
Donald is single with a current MAGI of $85,000. He wants to convert $20,000 to a Roth IRA in 2026.
| Metric | Value |
| Current MAGI | $85,000 |
| Conversion Amount | $20,000 |
| New MAGI | $105,000 (Below $106k IRMAA limit) |
Result: Donald pays 22% tax = $4,400. Because his new MAGI ($105,000) remains under the $106,000 single threshold, he pays $0 in IRMAA surcharges.
Common Roth Conversion Mistakes
1. Converting Just Above an IRMAA Threshold by a Few Hundred Dollars
IRMAA brackets are strict "cliff" thresholds. If a Roth conversion pushes your single MAGI to $106,001 (just $1 over the limit), you incur a full Tier 1 IRMAA surcharge of $81.20/month ($974.40/year) on Part B plus Part D surcharges.
The fix: Leave a $2,000 cushion below the IRMAA threshold when planning your conversion. Verify 2026 IRMAA brackets at medicare.gov Part B costs.
Official Government Sources Used in This Tool
| Source Name | What We Used It For | Direct Link |
|---|---|---|
| IRS Publication 590-A — Contributions to IRAs | Roth IRA conversion rules, income inclusion rules, and 5-year holding period requirements | IRS Pub 590-A |
| CMS Medicare IRMAA Surcharge Brackets 2026 | Official 2026 MAGI thresholds ($106k/$212k baseline) and surcharge tier amounts | medicare.gov Part B Costs |
Seniors Audit is an independent educational platform. We are not affiliated with, endorsed by, or connected to the IRS or CMS. All calculations use official tax code formulas and published IRMAA rates.
Frequently Asked Questions About Roth Conversions
What is a Roth IRA conversion?
A Roth IRA conversion is the process of moving pre-tax money from a Traditional IRA, 401(k), or 403(b) into a tax-free Roth IRA. The amount converted is treated as ordinary taxable income in the year of conversion, but all future growth and withdrawals in the Roth IRA are 100% tax-free for you and your heirs.
How does a Roth conversion affect Medicare IRMAA premiums?
Because a Roth conversion increases your Adjusted Gross Income (AGI) on Form 1040 Line 11, it also increases your Medicare MAGI. Social Security uses MAGI from two years prior (e.g., a 2024 conversion affects 2026 premiums) to set your Part B and Part D IRMAA surcharges. Converting too much in a single year can trigger an extra $81.20 to $443.90/month in Medicare premiums.
When is a Roth conversion worth the upfront tax bill?
A Roth conversion is typically worth it if: (1) You expect to be in a higher tax bracket in retirement than you are now; (2) You want to reduce future mandatory RMDs at age 73/75; (3) You have non-retirement cash available to pay the conversion tax bill; or (4) You want to leave tax-free inheritance to beneficiaries.
Can I pay the conversion tax out of the IRA funds being converted?
While legally possible, paying the tax out of the converted IRA funds is a major tax mistake. If you are under 59½, funds withheld to pay taxes are subject to a 10% early withdrawal penalty. Furthermore, using IRA money to pay taxes reduces the amount that moves into the tax-free growth vehicle.
Is there an annual dollar limit on how much I can convert to a Roth IRA?
No. Federal tax law puts zero limits on the total dollar amount or income level for Roth conversions. Unlike regular annual Roth IRA contributions (which have income limits and a $7,000–$8,000 annual cap), you can convert any amount from a Traditional IRA regardless of your income.
What is the 5-year rule for converted Roth IRA funds?
Each converted amount has its own 5-year holding period. If you withdraw converted principal before 5 years AND before age 59½, you may owe a 10% early withdrawal penalty. Once you reach age 59½, converted principal can be withdrawn penalty-free at any time.
How can I convert to a Roth IRA without triggering an IRMAA surcharge?
The key strategy is "bracket filling" — converting just enough each year to reach the top of your current tax bracket or the lower IRMAA threshold ($106,000 single / $212,000 joint in 2026) without crossing over the cliff.
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About This Educational Estimate: This tool is for educational purposes only. Seniors Audit uses the official formulas published by the relevant government agency, but results are estimates based on the information you entered. Rules, rates, and eligibility thresholds change annually and vary by individual circumstance.
If you have Medicare questions, a free SHIP counselor in your state can review your specific situation at no cost — find yours at shiphelp.org.
Seniors Audit is independent and not affiliated with any government agency or insurance company. We are not affiliated with, endorsed by, or connected to any government agency, insurance company, or financial services firm. All calculations use the official formulas and current figures published by the agencies listed above. We do not receive payment for referrals, leads, or any action taken by visitors to this site.