What Is IRMAA?
IRMAA — the Income-Related Monthly Adjustment Amount — is a surcharge that higher-income Medicare beneficiaries pay on top of their standard Part B (medical) and Part D (prescription drug) premiums. It is, in effect, a means-tested tax on Medicare coverage: the more income you report, the more you pay for the exact same benefits.
Most retirees never hear about IRMAA until the surcharge shows up on a Social Security statement or a Medicare bill — often two years after the financial decision that triggered it. By then the cost is locked in for the year and there is little to do but absorb it. Understanding how IRMAA works before you cross a threshold is one of the highest-value moves in retirement tax planning.
Who pays IRMAA?
Only a minority of beneficiaries pay IRMAA — those above the income thresholds. But the group most likely to be affected is exactly the group reading this: retirees with pensions, large traditional IRA or 401(k)/TSP balances, and meaningful taxable investment income.
How IRMAA Is Calculated
IRMAA is based on your Modified Adjusted Gross Income (MAGI). For IRMAA purposes, MAGI is a specific definition:
MAGI = Adjusted Gross Income (AGI) + tax-exempt interest income
That second piece surprises people. Interest from municipal bonds is exempt from federal income tax, but it is added back when Social Security calculates your IRMAA. So a portfolio built around "tax-free" muni income can still push you across an IRMAA line.
There is no deduction, exemption, or phase-in that softens the calculation. Social Security takes the single MAGI figure from your tax return, compares it to the bracket thresholds, and assigns you a tier.
The Two-Year Lookback — the Part Most People Miss
This is the single most important — and most counterintuitive — feature of IRMAA:
Your premiums are set using the tax return you filed two years earlier.
| Premium year | Tax return used |
|---|---|
| 2024 | 2022 return |
| 2025 | 2023 return |
| 2026 | 2024 return |
| 2027 | 2025 return |
The Social Security Administration (SSA) receives your income data from the IRS, and because there is a lag in tax filing and processing, it uses the most recent return available — which is two years old.
The planning implication is enormous. A financial decision you make today doesn't affect your Medicare premiums today. It affects them in two years — long after the decision feels relevant, and long after the advisor who recommended it has moved on to other things.
The delayed-damage problem
If you convert a large traditional IRA balance to Roth in 2026, that income lands on your 2026 tax return — which the SSA uses to set your 2028 Medicare premiums. The bill arrives 24 months downstream. Plan the conversion and the IRMAA consequence together, not separately.
2025 IRMAA Brackets and Surcharges
The table below shows the 2025 income brackets and the resulting monthly premiums. The brackets are based on 2023 MAGI (the two-year lookback in action). Income thresholds are indexed for inflation and adjust each year.
| 2025 MAGI (Single) | 2025 MAGI (Married Filing Jointly) | Part B Total / mo | Part D Surcharge / mo |
|---|---|---|---|
| $106,000 or less | $212,000 or less | $185.00 (standard) | $0.00 |
| $106,001 – $133,000 | $212,001 – $266,000 | $259.00 | +$13.70 |
| $133,001 – $167,000 | $266,001 – $334,000 | $370.00 | +$35.30 |
| $167,001 – $200,000 | $334,001 – $400,000 | $480.90 | +$57.00 |
| $200,001 – $500,000 | $400,001 – $750,000 | $591.90 | +$78.60 |
| Above $500,000 | Above $750,000 | $628.90 | +$85.80 |
Reading the table: a single filer with 2023 MAGI of $135,000 pays the second surcharge tier — $370.00/month for Part B plus a $35.30/month Part D add-on. That's roughly $2,460 more per year than the standard premium, for identical coverage.
Figures change every year
The dollar amounts above are 2025 figures. Both the standard premium and the bracket thresholds are updated annually. Always confirm the current-year numbers on Medicare.gov before relying on a specific threshold in your planning.
The Cliff Problem: One Dollar Over
IRMAA is not a gradual phase-in. It is a cliff. Cross a bracket boundary by a single dollar and you owe the entire surcharge for that tier — for the full year.
Consider a married couple, both on Medicare, with 2023 MAGI of exactly $266,000 — right at the top of the second bracket. One additional dollar of income pushes them into the third bracket. The result:
- Part B: jumps from $370.00 to $480.90/month, per spouse
- Part D: add-on jumps from $35.30 to $57.00/month, per spouse
That single dollar costs the household roughly $3,180 over the year (both spouses, Part B + Part D combined). The marginal "tax rate" on that last dollar is effectively over 300,000%.
This is why IRMAA planning is fundamentally about bracket awareness. The goal is rarely to minimize income outright — it's to avoid crossing a line by a small, avoidable margin.
What Counts Toward MAGI (and What Doesn't)
Because IRMAA is so cliff-sensitive, knowing exactly what feeds your MAGI matters.
Increases MAGI (can trigger IRMAA):
- Traditional IRA, 401(k), and TSP withdrawals
- Required Minimum Distributions (RMDs)
- Roth conversion amounts
- Capital gains, including a large home sale above the exclusion
- Pension and annuity income
- The taxable portion of Social Security benefits
- Interest, dividends, and rental income
- Tax-exempt municipal bond interest (added back)
Does not increase MAGI:
- Roth IRA withdrawals (qualified distributions are tax-free and excluded)
- Qualified Charitable Distributions (QCDs) — they satisfy an RMD without adding to AGI
- Return of principal / basis
- Health Savings Account (HSA) withdrawals for qualified medical expenses
- Loan proceeds and most gifts
Roth and QCDs are IRMAA tools
Income drawn from a Roth IRA doesn't count toward MAGI, and a Qualified Charitable Distribution lets charitably inclined retirees satisfy their RMD without inflating the income figure the SSA sees. Both are direct levers on IRMAA exposure.
Common IRMAA Triggers in Retirement
Retirees most often stumble into IRMAA through predictable, one-time events:
- Large Roth conversions. Converting too much in a single year can vault you across one or more brackets. See our guide to Roth conversions for how to size them by bracket.
- The first year of RMDs. When RMDs begin (currently age 73 for most), they can stack on top of existing income and push MAGI higher than retirees expect.
- Selling a home or a concentrated stock position. A capital gain above the exclusion can produce a one-year MAGI spike — and a one-year IRMAA surcharge two years later.
- The year a spouse passes away. The surviving spouse files as single going forward, and the single brackets are roughly half the joint brackets — so the same income can land in a higher tier.
- Inherited IRA distributions. Non-spouse beneficiaries draining an inherited account add taxable income that counts toward MAGI.
Strategies to Manage IRMAA
The good news: IRMAA is highly controllable with advance planning. The most effective strategies include:
Bracket-Aware Roth Conversions
Convert only enough each year to "fill" a target tax bracket and stay below the next IRMAA threshold. Converting earlier in retirement — before RMDs begin and while income is naturally lower — reduces future RMDs and the IRMAA they would trigger.
Realize Income in Lower-Income Years
Time discretionary income (conversions, gains, withdrawals) into years when your baseline income is low, so there's more room before the next cliff.
Use Roth and HSA Withdrawals Strategically
Drawing from Roth or HSA accounts in a high-income year lets you meet spending needs without adding to MAGI.
Spread Out Large Sales
Where possible, stage the sale of appreciated assets across multiple tax years rather than recognizing the entire gain at once.
Mind the Survivor Transition
Couples should plan for the eventual shift to single filing status, which compresses the brackets. This interacts with Social Security survivor benefits and can make pre-emptive Roth conversions especially valuable.
Appealing an IRMAA Determination
If your income has dropped because of a life-changing event, you don't have to accept a surcharge based on two-year-old income. You can request a reconsideration using Form SSA-44.
Qualifying life-changing events include:
- Marriage, divorce, or death of a spouse
- Work stoppage or reduction (including retirement itself)
- Loss of income-producing property
- Loss of a pension
- Receipt of a settlement from an employer due to closure or bankruptcy
Retirement is an appealable event
The year you retire, your income typically drops sharply — but your IRMAA is still based on your higher working-year income from two years prior. Filing Form SSA-44 to report the work-stoppage event can eliminate a surcharge you'd otherwise pay on income you no longer earn.
Coordinating IRMAA With Your Broader Tax Plan
IRMAA never operates in isolation. It interacts with:
- Social Security taxation — the same income that triggers IRMAA can also push more of your Social Security benefit into the taxable column.
- Capital gains rates — the 0%, 15%, and 20% long-term capital gains brackets have their own thresholds that overlap the IRMAA decision.
- Ordinary income tax brackets — bracket-filling for income tax and bracket-avoidance for IRMAA often pull in different directions.
The right move is rarely to optimize any one of these alone. A multi-year projection that models income tax, Social Security taxability, RMDs, and IRMAA together is what separates a coordinated plan from a series of well-intentioned but conflicting decisions.
The Bottom Line
IRMAA is a cliff, not a slope; it's driven by a MAGI figure that includes tax-exempt interest; and it's set by a tax return filed two years in the past. Those three facts make it one of the easiest costs to stumble into — and one of the most avoidable with planning.
Before any large Roth conversion, asset sale, or withdrawal, map the decision forward two years and check it against the IRMAA brackets. The few minutes of analysis can save thousands of dollars in surcharges you'd otherwise never see coming.
This article is for educational purposes only and does not constitute tax or financial advice. IRMAA brackets, premiums, and rules change annually. Consult a qualified tax professional or financial advisor and verify current figures on Medicare.gov before making decisions.