IRMAA Calculator 2026 — Will Your Income Trigger a Medicare Surcharge?
Enter your retirement income sources and instantly see your IRMAA tier, monthly Medicare premium, and how much Roth conversion headroom you have before the next cliff
Reviewed for accuracy June 25, 2026 by Gary Sing
Medicare IRMAA thresholds are separate for single and married-filing-jointly returns. Both spouses pay the surcharge if their joint income crosses the threshold.
Enter your gross (before Medicare deduction) annual SS benefit. The calculator determines how much is taxable using the IRS combined income formula.
All distributions from traditional pre-tax retirement accounts — Required Minimum Distributions plus any additional withdrawals. Fully taxable and fully counted in MAGI.
Pension income, part-time wages, capital gains, dividends, taxable interest, and any other income sources. Do not include Roth IRA withdrawals (tax-free, not in MAGI).
Municipal bond interest is excluded from regular AGI but is added back for IRMAA MAGI calculation. Include it here if you hold muni bonds.
Optional. Enter any amount you plan to convert from a traditional IRA or 401(k) to Roth. Conversion income counts dollar-for-dollar toward MAGI and can trigger or push you to a higher IRMAA tier.
How to use IRMAA Calculator
Free 2026 IRMAA calculator. Enter Social Security, RMDs, and other income to see your Medicare surcharge tier, Part B and Part D premium costs, annual extra cost vs standard rate, and how much Roth conversion you can do before crossing the next IRMAA cliff.
The IRMAA Calculator estimates your 2026 Medicare surcharge based on your retirement income. Enter your Social Security benefit, 401(k) and IRA withdrawals, and other income sources — the calculator computes your Modified Adjusted Gross Income (MAGI), identifies which of six IRMAA tiers applies, and shows your exact Part B and Part D monthly premiums. It also calculates how much Roth conversion headroom you have before crossing the next IRMAA cliff — one of the most valuable planning numbers in retirement tax strategy.
How to use this IRMAA Calculator
- 1Select your Medicare filing status: married filing jointly (threshold doubles) or single.
- 2Enter your annual Social Security benefit as a gross dollar amount — before Medicare premium deductions.
- 3Enter total 401(k), IRA, and RMD withdrawals for the year. These count dollar-for-dollar toward MAGI.
- 4Enter other taxable income: pensions, part-time wages, dividends, and capital gains. Do not include Roth IRA withdrawals — those are tax-free and do not count in MAGI.
- 5Enter any tax-exempt (municipal bond) interest — it is excluded from regular AGI but added back for the IRMAA MAGI calculation.
- 6Optionally enter a planned Roth conversion to see whether it would push you into a higher tier or consume your remaining headroom.
How IRMAA MAGI is calculated
IRMAA uses Modified Adjusted Gross Income (MAGI), which for Medicare purposes equals AGI plus tax-exempt interest income. Social Security is partially taxable based on the IRS combined income formula: up to 85% of SS benefits are included once combined income exceeds $34,000 (single) or $44,000 (married). RMD and IRA withdrawals are fully included. Roth IRA withdrawals and qualified HSA distributions are not included.
| Variable | Meaning |
|---|---|
| Provisional income | Other income + 50% of SS benefit — triggers the SS taxability thresholds |
| Taxable SS | 0–85% of gross SS benefit, depending on provisional income level |
| IRA / RMD withdrawals | Fully taxable; counted 100% in MAGI |
| Tax-exempt interest | Municipal bond interest — excluded from AGI but added back for IRMAA |
| Roth withdrawals | Not included — tax-free and excluded from IRMAA MAGI entirely |
IRMAA worked example: married couple, $1.8M 401(k) at age 73
- 01Social Security: $62,400/year gross ($5,200/month × 2 spouses).
- 02401(k) first-year RMD: $67,925 ($1,800,000 ÷ 26.5 IRS divisor at age 73).
- 03Provisional income = ($67,925 + $0 other) + $62,400 × 0.5 = $99,125.
- 04Taxable SS = 85% of $62,400 = $53,040 (provisional well above $44k MFJ limit).
- 05MAGI = $53,040 (taxable SS) + $67,925 (RMD) = $120,965.
- 06Filing jointly: $120,965 is between $109,001 and $137,000 → Tier 1.
- 07Part B monthly: $284.10 per person × 2 = $568.20/month as a couple.
- 08Extra cost vs standard: ($284.10 − $202.90) × 2 × 12 = $1,948/year.
Result
This couple pays $1,948/year more in Part B premiums than the standard rate, plus Part D surcharges — triggered entirely by the RMD stacking on top of Social Security. Roth conversions between ages 64–70 could have reduced the 401(k) balance enough to bring the RMD below $56,000, keeping MAGI under $109,000 and eliminating the surcharge entirely.
What drives IRMAA surcharges higher?
2-year lookback rule
2026 IRMAA premiums are determined by your 2024 tax return MAGI. Income events in 2024 — a Roth conversion, large RMD, or property sale — raise 2026 Medicare costs. You cannot fix this retroactively; forward planning 2 years out is essential.
Hard cliff, not a ramp
IRMAA is a step function. Earn $1 over the threshold and the full surcharge applies for the entire year. This makes the income just below each threshold extremely valuable to protect — the marginal cost of the dollar that crosses the cliff is hundreds or thousands of times higher than a normal tax dollar.
RMD growth accelerates over time
As you age, the IRS life expectancy divisor decreases while the 401(k) balance (if invested) may still be growing. RMDs as a percentage of balance rise from ~3.8% at 73 to over 10% at 90. The IRMAA problem compounds if the pre-tax balance is not reduced through Roth conversions in the early retirement window.
Roth conversion timing matters
Conversions increase MAGI in the year they occur — and raise Medicare premiums two years later. The optimal conversion window is before age 65 (pre-Medicare), and cautiously during ages 65–72 staying below the current tier threshold.
SS taxability cascade
Before 85% of Social Security is taxable, adding $1 of other income increases provisional income by $1 and may add up to $0.85 of taxable SS on top. This means each dollar of Roth conversion can add up to $1.85 to MAGI until SS reaches its 85% maximum — the calculator accounts for this conservatively in the Roth headroom estimate.
Both spouses pay
If both spouses are enrolled in Medicare, both pay IRMAA on their own Medicare premiums. A married couple crossing the threshold pays the surcharge twice — once for each spouse. The joint income threshold is set at exactly double the single threshold.
Tips and things to know
- ✓The single most effective long-term strategy is Roth conversions during ages 64–70, when earned income, Social Security, and RMDs are all zero — leaving maximum room to convert at low tax rates.
- ✓File Form SSA-44 with the Social Security Administration if your income dropped significantly due to retirement, a spouse's death, divorce, or reduced work hours. Medicare will use a more recent (lower) income year and reduce your premiums.
- ✓Qualified Charitable Distributions (QCDs) up to $108,000/year satisfy RMDs and are excluded from AGI entirely — a dollar-for-dollar MAGI reduction for retirees who give to charity.
- ✓Municipal bond interest adds to IRMAA MAGI even though it is excluded from regular AGI. At higher income levels, the IRMAA cost of muni bonds can exceed their after-federal-tax yield advantage.
- ✓The IRMAA threshold for 2028 is based on 2026 income — plan your conversions and distributions this year with 2028 Medicare premiums in mind, not just this year's tax bill.
Official resources and further reading
CMS — 2026 Medicare Part B Premium Announcement
Official CMS announcement of 2026 Part B premiums and IRMAA surcharge amounts by income tier.
SSA — IRMAA Overview and Appeals (Form SSA-44)
Social Security Administration explanation of IRMAA, the two-year lookback rule, and how to file a life-changing event appeal using Form SSA-44.
IRS — Social Security Taxability (Publication 915)
IRS Publication 915 explaining the combined income formula that determines what percentage of Social Security benefits is taxable — the main driver of IRMAA MAGI.
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Frequently asked questions
IRMAA (Income-Related Monthly Adjustment Amount) is a surcharge added to Medicare Part B and Part D premiums when your Modified Adjusted Gross Income exceeds certain thresholds. In 2026, the first threshold is $109,000 for single filers and $218,000 for married couples filing jointly. The surcharge is a hard cliff — $1 over the line triggers the full extra premium for the entire year. Medicare uses your income from 2 years prior to set the current year's surcharge.
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