IRMAA and Medicare surcharges
High income in retirement doesn't just mean higher taxes. It means higher Medicare premiums too. IRMAA surcharges use a 2-year lookback that catches many retirees off guard.
What is IRMAA?
IRMAA (the Income-Related Monthly Adjustment Amount) is a surcharge added to your Medicare Part B and Part D premiums if your income exceeds certain thresholds. It's not a separate tax or a penalty. It's a higher premium that Medicare charges higher-income beneficiaries, and it can add anywhere from $81 to $487 per month on top of the standard Part B premium of $202.90/mo (2026).
IRMAA applies per person, not per household. If both you and your spouse are enrolled in Medicare and your joint MAGI (modified adjusted gross income) exceeds the threshold, you each pay the surcharge individually. A married couple in Tier 4 can pay over $10,000 per year in extra Medicare premiums alone: money that comes straight off the top of your retirement income.
Most retirees don't plan for IRMAA because it feels like a minor detail compared to taxes, Social Security timing, and withdrawal strategy. But it's effectively a hidden marginal tax on retirement income: one that stacks on top of federal and state income taxes and can change the math on Roth conversions, capital gains harvesting, and RMD management in meaningful ways.
How IRMAA is calculated
IRMAA is calculated by the Social Security Administration each fall using the most recent tax return the IRS has on file. SSA pulls your MAGI from that return, compares it to the published bracket thresholds for the upcoming year, and mails an Initial Determination notice in November or December telling you what you'll pay starting in January. The calculation runs annually, so your bracket can move up or down each year as your reported MAGI changes.
The income figure IRMAA uses is MAGI (modified adjusted gross income), not plain AGI. For IRMAA purposes, MAGI is defined narrowly: it equals your AGI from Form 1040 line 11 plus tax-exempt interest from line 2a. That's the entire modification. Unlike the broader MAGI definitions used for ACA subsidies or IRA contribution limits, IRMAA's MAGI does not add back student loan interest, foreign earned income, or other items. The one trap to watch: municipal bond interest that escapes federal income tax still counts toward your IRMAA threshold.
Because the calculation uses a return that's already filed and final, you cannot reduce IRMAA after the fact by amending your strategy. The only way to lower a determination is to either appeal it (if the return is wrong, outdated, or was affected by a qualifying life-changing event) or wait for the next year's recalculation to reflect lower income.
The 2-year lookback
IRMAA doesn't use your current-year income. It uses your modified adjusted gross income from your tax return filed two years prior. Your 2026 Medicare premiums are based on your 2024 MAGI. Your 2027 premiums are based on your 2025 MAGI. This creates a planning lag that many retirees don't anticipate, income decisions you make today won't affect your Medicare premiums for two years.
The lookback catches people who do large Roth conversions, sell a home with gains above the $250K/$500K exclusion, realize significant capital gains in a single year, or take a lump-sum pension distribution. In each case, the retiree sees the income event as a one-time occurrence, but Medicare sees it as evidence of higher income and charges accordingly: two years later, when the original context is long forgotten.
There is one escape valve. If you experienced a "life-changing event," you can file Form SSA-44 to request that Social Security use a more recent year's income instead of the 2-year-old return. Qualifying events include marriage, divorce, death of a spouse, work stoppage, work reduction, loss of income-producing property, and loss of pension income. Retirement itself counts as a work stoppage, but only in the year you actually stop working. You can't file SSA-44 because your income happened to be lower this year; it must be tied to a qualifying event.
IRMAA brackets and costs
IRMAA has five surcharge tiers above the standard premium, each triggered by specific MAGI thresholds. The brackets below show 2026 thresholds for single filers. Married filing jointly thresholds are exactly double. Married filing separately uses a different, much steeper schedule, covered in IRMAA for married couples.
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Standard MAGI ≤ $109,000 +$0/yr
The baseline. The goal for income management in Medicare years.
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Tier 1 $1 over $109,000 +$1,148/yr
The first cliff: $1 over the threshold costs $974/yr in Part B alone.
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Tier 2 $1 over $137,000 +$2,885/yr
The surcharge alone now equals the standard premium.
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Tier 3 $1 over $171,000 +$4,620/yr
The first tier where the surcharge exceeds the base Part B premium itself.
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Tier 4 $1 over $205,000 +$6,355/yr
An unusually wide bracket. Any MAGI from $205K to $500K lands here.
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Tier 5 $1 over $500,000 +$6,888/yr
The ceiling. Surcharges are flat above $500K, no further tiers.
Figures shown are per person, single filers. Married filing jointly: thresholds double ($109K becomes $218K, etc.), and if both spouses are on Medicare the household pays roughly 2× the surcharge shown. See IRMAA for married couples for the full schedule.
The surcharge figures in the ladder above are Part B IRMAA + Part D IRMAA combined, per person. A married couple both on Medicare in Tier 3 pays roughly $9,240/yr in combined IRMAA surcharges, on top of the $4,870 standard Part B premium they already pay between them ($202.90 × 2 × 12). That's about $14,100/yr in Medicare premiums paid to CMS, before whatever their Part D plan charges them directly.
Part D IRMAA works the same way. The same MAGI thresholds that trigger Part B surcharges also trigger a Part D surcharge, ranging from about $14.50/mo at Tier 1 to roughly $87/mo at Tier 5 (2026). One important difference: the Part D surcharge is paid directly to Medicare, not to your prescription drug plan, and it stacks on top of whatever monthly premium your plan charges. It applies whether you have a standalone Part D plan or a Medicare Advantage plan that includes drug coverage. If you drop Part D entirely, you avoid the Part D surcharge but may face a late-enrollment penalty later. The staircase chart shows Part B monthly totals only (because Part D plan premiums vary by insurer); the annual figures in the cliff ladder above already include the Part D IRMAA component.
IRMAA for married couples
IRMAA treats married couples in three very different ways depending on filing status and which spouses are enrolled in Medicare. Getting the structure right matters: the same household income can produce a wildly different premium bill. The three staircases below put them side by side, using the same tier numbering as the cliff ladder above.
Married, filing jointly
Thresholds 2× · 6 steps
Joint MAGI sets the bracket; each enrolled spouse pays the per-person surcharge. Couple in Tier 3, both enrolled: $9,240/yr household (Part B + Part D IRMAA).
Only one spouse enrolled
Same tiers · one payer
Joint MAGI still sets the tier, but only the enrolled spouse pays. Tier 3 household: $4,620/yr (Part B + Part D IRMAA). Dashed line: what both-enrolled would cost.
Married, filing separately
3 tiers · no middle
No middle ground: $1 over $109K triggers the full Tier 4 Part B surcharge per person ($5,356/yr). Dashed line: what the same income would pay as MFJ.
The MFS structure exists to prevent married couples from filing separately to game IRMAA. If you're considering MFS for unrelated reasons (separate-property states, income-driven student loan repayment, liability separation), run the Medicare cost before deciding. It often exceeds the tax savings.
What triggers IRMAA
IRMAA is based on your modified adjusted gross income, which includes nearly every form of income: wages, IRA and 401(k) withdrawals, pension income, the taxable portion of Social Security benefits, capital gains, rental income, business income, and, critically, Roth conversions. Roth conversions are the biggest planning gotcha because the entire converted amount adds to your MAGI in the conversion year, even though the purpose of the conversion is to reduce future taxable income.
Large one-time income events are particularly dangerous. Selling a business, selling a home with gains above the $250K/$500K exclusion, exercising stock options, or inheriting a traditional IRA (which under the SECURE Act must be fully distributed within 10 years) can all spike your MAGI into higher IRMAA tiers for one or two years. Because of the 2-year lookback, the premium impact doesn't hit until you may have forgotten about the triggering event entirely.
Required minimum distributions starting at age 73 are another common trigger. RMDs grow larger each year as the divisor shrinks, and when combined with Social Security income, they can push retirees into IRMAA brackets they never expected to reach. This creates a double penalty: the forced withdrawal generates both higher income taxes and higher Medicare premiums. Retirees with large traditional IRA balances are especially vulnerable: a $1.5M IRA at age 73 requires an RMD of roughly $58,000, which combined with Social Security can easily exceed the first IRMAA threshold.
Strategies to avoid IRMAA
IRMAA planning is really income timing and placement planning. The goal is to control your MAGI in the years that feed into IRMAA calculations, either by shifting income to years before Medicare starts, converting assets to tax-free accounts, or using deductions and strategies that reduce AGI directly.
The most powerful strategies combine multiple approaches: doing Roth conversions before 63 to reduce future RMDs, then managing withdrawals and capital gains carefully during Medicare years to stay below the nearest IRMAA threshold. Even small adjustments matter because of the cliff nature of the brackets: keeping MAGI $1 below a threshold saves the full surcharge for that tier.
Here are the most effective tools for managing IRMAA exposure across your retirement timeline.
Convert before age 63 to shrink your tax-deferred balance before the lookback window reaches Medicare years. Often the single highest-value IRMAA strategy because it reduces future RMDs at the source. See the 2-year lookback section for why 63 is the cutoff.
In Medicare years, manage your total MAGI to stay below the nearest IRMAA threshold. Sometimes withdrawing $1,000 less saves $1,000+ in Medicare surcharges. Mix Roth withdrawals (which don't count toward MAGI) with traditional withdrawals to fine-tune your income. Consider delaying capital gains realization or spreading it across multiple years.
QCDs at age 70½+ let you donate directly from your IRA to charity, satisfying your RMD without adding to AGI. This can keep you below an IRMAA threshold while fulfilling your required distribution and supporting charities you care about. The annual QCD limit is $108,000 (2025), which can offset a significant portion of large RMDs.
If you recently retired, your 2-year-ago income doesn't reflect your current situation. File SSA-44 with proof of retirement (a work stoppage event) to request that Social Security use your current-year income instead. This can immediately drop you to the standard premium. It's one of the few ways to override the lookback, but it only works with qualifying life-changing events.
IRMAA planning works best when integrated with your overall tax reduction strategy and Roth conversion plan. The math is interconnected: a Roth conversion that pushes you into a higher tax bracket but keeps you below an IRMAA cliff may still be worth doing. A conversion that triggers both a higher tax bracket and a higher IRMAA tier may not. Running the numbers year by year is the only way to find the optimal balance.