IRMAA Cliffs in 2026: What Going $1 Over Each Tier Costs, and Which Moves Push Typical Retirees Over

Published 2026-10-11. Tax year 2026 (the return filed in early 2027).

What does going $1 over an IRMAA tier cost in 2026?

Far more than the dollar itself. A single filer whose 2026 MAGI ends one dollar above $109,000 pays $1,148.40 more a year in Part B and Part D surcharges; the federal income tax on extra income at that point is 24.2 cents a dollar ($242 on the next $1,000). For a couple both on Medicare the first cliff, above $218,000, costs $2,296.80, as much as the federal tax on about $9,321 of extra income. Of the moves tested on six typical retiree households, 11 of 22 cross a tier; a $50,000 Roth conversion crosses for 4 of 6. The surcharge is charged in 2028, on the premium tiers then in force; this study prices it on the 2026 tiers.

Your MAGI and the room to the next tier: the IRMAA calculator
Free: your 2026 IRMAA MAGI, the tier it lands in, and the headroom to the next cliff.

The cliffs: what the crossing dollar costs

Medicare's income-related monthly adjustment amounts (IRMAA) are added to the Part B and Part D premiums of anyone whose modified adjusted gross income from two years earlier is above a tier floor: AGI plus tax-exempt interest (20 CFR 418.1010(b)(6)). They are not phased in: one dollar above a floor brings the whole tier's surcharge for the year, for each person on Medicare in the household (CMS 2026 Part B premiums; Part D income-related amounts). Married people who file separately and lived together at any time in the year have only two tiers, starting near the top of the scale (20 CFR 418.1115).

The reference households: Single, 70, $36,000 of Social Security; Married filing jointly, 70 and 68 (both on Medicare), $60,000 of Social Security; Married filing separately, lived with the spouse, 70, $30,000 of Social Security. All of their other income is IRA withdrawals; for each tier the study finds the IRA income that puts MAGI exactly at the floor and adds one dollar, $1,000 and $10,000.

The federal tax on the single crossing dollar is $0 or a few cents: below $100,000 of taxable income a return uses the IRS Tax Table, whose tax moves in $50 steps, so the next $1,000 is the fairer measure of the income tax at that point. Even $10,000 over a floor costs a joint filer 48% of it at the first cliff, the surcharge and the federal tax together. The last column restates the cliff as income: the surcharge equals the federal tax this household pays on that much extra income at its marginal rate.

Which moves push typical retirees over

Six households, every one on Medicare and below a tier. Where a household has an IRA balance, its 2026 RMD (the engine's Uniform Lifetime Table RMD, rounded up to the cent) is part of its year; the last move for those households compares the year without the RMD and with it.

Where a move crosses a tier, the surcharge is up to 26% of its total cost (T3: $30,000 long-term capital gain). The room column is the largest Roth conversion that keeps MAGI at the floor: sized one dollar lower, the same conversion costs only its income tax. A capital gain counts in MAGI like any other income, and so does tax-exempt interest. A qualified charitable distribution from an IRA does not (it is left out of income, IRC §408(d)(8)).

2026 income, 2028 premiums

The 2026 premiums are set by 2024 tax returns; the MAGI of 2026 sets the surcharge paid in 2028, on tiers CMS will publish in late 2027 (SSA POMS HI 01101.020; the 2026 Part B premium notice). The tier floors are indexed to inflation (42 U.S.C. §1395r(i)), so the 2028 floors will most likely be higher; the dollars on this page are the 2026 tiers applied to 2026 income, the convention of QuantCalc's IRMAA calculator. A drop in income after a life-changing event, such as stopping work or the death of a spouse, can be reported to SSA to have the surcharge figured on the newer year (our IRMAA appeal guide).

Related: The 2026 IRMAA cliff map · What crossing a tier costs a Roth conversion · 2026 IRMAA brackets · The tax on a 2026 RMD

Download the data

Every case on this page, with its inputs: irmaa-one-dollar-over-2026.csv (the 12 cliffs) · irmaa-one-dollar-over-2026-moves.csv (the 22 moves) · irmaa-one-dollar-over-2026.json (cliffs, households and moves, CC0). Dollar amounts in USD; rates and shares as decimals.

Questions

What happens if I go $1 over an IRMAA bracket?

You pay the whole tier's surcharge for the year, for each person on Medicare. For a single filer, $1 over $109,000 of 2026 MAGI adds $1,148.40 of Part B and Part D surcharges (on the 2026 tiers), while the federal income tax at that income is about 24.2 cents a dollar. For a couple both on Medicare, $1 over $218,000 adds $2,296.80.

Is IRMAA worse than income tax?

At the cliff, by far: the surcharge for the first dollar over is thousands of times the income tax on a dollar. Spread over a larger overshoot it fades: on the next $10,000 above the first single-filer floor the surcharge and the federal tax together are 35% of the $10,000 for the reference household.

Will a Roth conversion push me into IRMAA?

It can, two years later. Of six typical retiree households, a $25,000 conversion crosses a tier for 3 and a $50,000 conversion for 4. Each household's room to the next tier is in the table; a conversion sized to that room avoids the surcharge.

Do capital gains and RMDs count toward IRMAA?

Yes. Both are in AGI and so in IRMAA MAGI. A $30,000 long-term gain crosses a tier for 3 of the six households, and the 2026 RMD by itself for 1 of the 4 with one.

Method and sources

Every figure was computed by QuantCalc's open federal tax engine (2.3.2) and its IRMAA module, the ones the free IRMAA calculator runs, then recomputed by the C engine behind the federal tax API and its IRMAA table, from independently written requests, agreeing to the cent. IRMAA MAGI is the engine's (AGI plus tax-exempt interest); the surcharge is the annual Part B plus Part D adjustment per person on Medicare, on the 2026 tiers. A household "at the floor" is the largest whole-dollar IRA income that keeps MAGI at or below the floor (below it, for the top tier, which starts at the floor itself), checked to hold at the published dollar and to break one dollar above. Federal tax uses the IRS Tax Table below $100,000 of taxable income, as a return does. The rules:

• 2026 Medicare Parts A & B Premiums and Deductibles
• 20 CFR 418.1010: Definitions ((b)(6), modified adjusted gross income)
• 20 CFR 418.1115: What are the modified adjusted gross income ranges?
• POMS HI 01101.020: IRMAA sliding scale tables
• Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026 (CMS-8091-N)
• 42 U.S.C. 1395r
• 26 U.S. Code § 408
• Publication 915, Social Security and Equivalent Railroad Retirement Benefits
• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments)
• 26 U.S. Code § 151
• 26 CFR 1.401(a)(9)-9: Life expectancy and distribution period tables

What is not modelled

• The households are illustrations, not averages: the standard deduction, no other income than shown, every person 65 or older and on Part B and Part D.
• The 2026 tiers and premiums: the surcharge 2026 income sets is charged in 2028 on tiers not yet published.
• State income tax is not included; it adds to the income-tax side, not to the surcharge.
• The married-filing-separately household lived with the spouse during the year; separated spouses who lived apart all year use the single tiers.
• Each RMD is the Uniform Lifetime Table RMD on the stated December 31, 2025 balance, of the older spouse on a joint return.

An estimate, not tax advice. These are computed examples for the 2026 tax year from QuantCalc's open tax engines (federal 2.3.2, state 1.14.2). Your own return depends on facts these examples do not include. Check any decision with your tax preparer before acting.

@misc{quantcalc2026irmaacliffsin2026what1overcostsagainstth,
  title  = {IRMAA Cliffs in 2026: What $1 Over Costs Against the Income Tax on It, and the Moves That Push Retirees Over},
  author = {{QuantCalc Research}},
  year   = {2026},
  url    = {https://quantcalc.app/research/irmaa-one-dollar-over-2026/},
  note   = {Accessed <date>}
}