One dollar of income, $1,148 of Medicare premium

Six point one million people will pay it this year.

That is the Trustees' figure for the number of Medicare beneficiaries facing the Part B income-related monthly adjustment amount in 2026, published in Table V.E3 of the 2026 report. Last year the same table shows 5.1 million. The money collected above the standard premium goes from $14.1bn to $18.8bn, a rise of 33 percent in one year on a charge that did not change in design at all.

The surcharge is known by its acronym, IRMAA, and it is the least understood line in American retirement money. Almost every page written about it publishes the bracket table and stops. The bracket table is the easy part. What actually catches people is the structure underneath it: a cliff rather than a slope, a two-year lookback, a definition of income that is not the definition used anywhere else in health policy, and a second cost that nobody prices at all.

What is Medicare IRMAA?

IRMAA is an additional monthly premium for Medicare Part B and Part D, paid by beneficiaries whose modified adjusted gross income exceeded a threshold on the federal tax return filed two years earlier. The Social Security Administration makes the determination from IRS data. CMS sets the amounts each autumn. It has applied to Part B since 2007 and to Part D since 2011.

It is not a tax and it is not means testing in the usual sense. Under 20 CFR 418.1120 the federal government normally subsidises 75 percent of the cost of Part B coverage, leaving the beneficiary paying 25 percent through the standard premium. The surcharge does not add a fee on top of that arrangement. It changes the split. A beneficiary above the first threshold pays 35 percent of the estimated total cost of their own coverage instead of 25 percent, and the government pays 65 instead of 75. Above the highest threshold the beneficiary pays 85 percent and the subsidy falls to 15.

That framing is the government's own, stated in the 2026 premium notice, and it explains something the bracket tables never do. The surcharge amounts rise every year not because Congress raises them but because the cost of Part B rises and the percentages are fixed to that cost.

What are the 2026 Medicare IRMAA brackets?

For 2026 the first threshold is a 2024 modified adjusted gross income above $109,000 filing singly or above $218,000 filing jointly. The standard Part B premium is $202.90 a month. Above the thresholds the total Part B premium runs $284.10, $405.80, $527.50, $649.20 or $689.90, with a separate Part D surcharge of $14.50 to $91.00 added to whatever the plan charges.

2024 income, single	2024 income, joint	Part B total	Part D surcharge
$109,000 or less	$218,000 or less	$202.90	none
$109,001 to $137,000	$218,001 to $274,000	$284.10	$14.50
$137,001 to $171,000	$274,001 to $342,000	$405.80	$37.50
$171,001 to $205,000	$342,001 to $410,000	$527.50	$60.40
$205,001 to $499,999	$410,001 to $749,999	$649.20	$83.30
$500,000 or more	$750,000 or more	$689.90	$91.00

Married filing separately is the punitive case and it is easy to miss. Where the couple lived together at any point in the tax year there are only two steps rather than five: above $109,000 the total Part B premium is $649.20, and at $391,000 it is $689.90. A separate return does not split the income into two smaller shares. It skips four brackets.

The Part B annual deductible is $283.00 for everyone in 2026, up from $257.00. The deductible is not income-related and the surcharge does not change it.

How is the surcharge actually calculated?

CMS computes a monthly actuarial rate for aged enrollees, which for 2026 is $405.40 and represents half the estimated cost per aged enrollee. The standard premium is 25 percent of the full cost. Each surcharge tier replaces that 25 percent with 35, 50, 65, 80 or 85 percent, so the published dollar figures are outputs of a percentage, not a schedule Congress votes on.

The arithmetic closes, and it is worth walking once because it explains why the numbers look slightly odd. Twice the aged actuarial rate is $810.80. A quarter of that is $202.70. The published standard premium is $202.90, and the Trustees report says why: the 2026 premium includes $0.20 of repayment owed to the Treasury under the Bipartisan Budget Act of 2015, which required that the premium be increased by $3.00 a month until two earlier transfers were paid back. This is the final stretch of that repayment. Take the twenty cents out and the premium is exactly a quarter of the cost. That reconciliation is ours, performed on the published figures.

One consequence follows immediately. Because the tiers are percentages of a rising cost, the surcharge grows faster in dollars than the standard premium does. The 2026 standard premium rose $17.90 over 2025. The top-tier total rose $61.00, from $628.90 to $689.90.

Which tax year does Medicare use for IRMAA?

The tax year two years before the premium year. The 2026 surcharge is set from the 2024 return. Where the IRS has not supplied that year, 20 CFR 418.1135(b) directs the agency to use the year three years prior, which is 2023, and then to correct retroactively once the 2024 data arrives.

The lookback is the single most consequential feature of the design. A person who retired in 2025 pays a 2026 premium set by the income they earned while still working in 2024. Someone who sold a business, converted a retirement account or realised a large capital gain in 2024 pays for it across all twelve months of 2026, whatever their income is now.

There is also a rule for non-filers that almost nobody publishes. Under 418.1135(f), where a beneficiary failed to file for a year after 2004 and the IRS reports income above the threshold, the agency applies the highest surcharge percentage available for that filing status. Not the correct band. The top one, until corrected.

What counts as income for IRMAA?

Modified adjusted gross income for this purpose is adjusted gross income plus five specific categories: tax-exempt interest, income from United States savings bonds used for higher education, foreign earned income, income from Guam, American Samoa or the Northern Mariana Islands, and income from Puerto Rico. Form SSA-44 states it more simply as line 11 of Form 1040 plus line 2a.

That definition is narrower than the modified adjusted gross income used for insurance subsidies under the Affordable Care Act, and the difference matters in one direction that surprises people. Municipal bond interest is tax-exempt on the return and it is added back here. A portfolio built to keep taxable income down can still push a household over a threshold on interest it never paid tax on.

Nothing else is added. Social Security benefits enter only to the extent they are already taxable and included in adjusted gross income. There is no separate add-back.

Why does one dollar over a threshold cost so much?

Because the structure is a step, not a rate. There is no phase-in and no marginal band. A single dollar of income above $109,000 filing singly moves the entire premium to the next tier for the whole of the premium year, on both Part B and Part D.

At the first step that is $81.20 a month on Part B and $14.50 on Part D, which is $95.70 a month or $1,148.40 across the year. For a married couple where both are enrolled, both premiums move, so the household cost of that one dollar is $2,296.80. Those are our multiplications of the published monthly figures.

The gap at the top is larger still. A beneficiary in the highest band pays $689.90 a month against a standard $202.90, a difference of $487.00 a month or $5,844.00 a year, for identical coverage. Add the Part D surcharge at $91.00 a month and the annual difference reaches $6,936.00 per person.

What does IRMAA cost beyond the surcharge itself?

It removes the hold-harmless protection. Section 1839(f) of the Social Security Act limits the Part B premium increase for most beneficiaries to the dollar increase in their Social Security benefit, so a premium rise can never cut a monthly check. The 2026 notice states plainly that the provision does not apply to beneficiaries required to pay an income-related adjustment.

This is the second cost and it is invisible in every bracket table published. The Trustees report puts roughly 70 percent of Part B enrollees inside hold-harmless protection, and names surcharge payers among the roughly 30 percent outside it, alongside new enrollees, people who do not receive a Social Security check and dual Medicare-Medicaid beneficiaries.

The practical effect compounds. In a year when the Part B premium rises faster than the Social Security cost-of-living adjustment, most beneficiaries are shielded from the difference and surcharge payers absorb all of it. Crossing the threshold therefore does two things at once. It adds a charge, and it withdraws a cap.

Who actually pays it, and how fast is that number growing?

CMS puts it at roughly 8 percent of people with Part B and approximately 8 percent of people with Part D. In absolute terms the Trustees count 6.1 million Part B surcharge payers in 2026 against 1.7 million when the charge began in 2007, and project 10.2 million by 2035.

Year	Part B payers	Part B collected	Part D payers	Part D collected
2007	1.7m	$0.7bn	not yet in force	not yet in force
2011	1.6m	$2.3bn	0.9m	$0.3bn
2019	4.3m	$8.4bn	3.4m	$1.6bn
2025	5.1m	$14.1bn	4.5m	$2.4bn
2026	6.1m	$18.8bn	5.3m	$3.1bn
2035	10.2m	$55.8bn	9.3m	$15.9bn

Two features of the design do most of the work here, and both are stated in the documents rather than inferred. The thresholds were frozen entirely from 2011 through 2019, and are adjusted for inflation thereafter under 20 CFR 418.1105, by the increase in the Consumer Price Index, rounded to the nearest $1,000, published each September.

The second is narrower and sharper. The Bipartisan Budget Act of 2018 created the top band at $500,000 and $750,000, and specified that those two figures are not inflation adjusted until 2028. They have therefore sat unchanged for eight years while the first threshold rose from $85,000 in 2019 to $109,000 now, a rise of 28.2 percent on our calculation. The floor moves. The ceiling does not.

What happens to Part D surcharges in 2030?

They roughly triple. The Part D surcharge is the difference between the applicable percentage and 25.5 percent, applied to the national average monthly bid amount adjusted for reinsurance. The Inflation Reduction Act of 2022 resets how the base beneficiary premium is set in 2030, and the Trustees project the first-tier Part D surcharge rising from $17.30 in 2029 to $51.70 in 2030 as a result.

The whole Part D table moves with it. The top tier goes from $108.40 to $224.00. Aggregate Part D surcharge collections jump from $4.6bn in 2029 to $10.8bn in 2030 on the Trustees' intermediate assumptions, while the number of people paying rises only from 6.7 million to 7.1 million. The Trustees attach a footnote to Table V.E4 saying exactly this, and it is the clearest scheduled change in the whole scheme.

It is worth setting the current numbers against the thing being surcharged. The 2026 Part D base beneficiary premium is $38.99, and the Trustees project the average premium actually paid at $27.22 because beneficiaries tend to select cheaper plans. The top Part D surcharge is $91.00. The federal addition, in other words, is already more than three times the average plan premium, and it is charged at the same flat amount whether the plan costs $80 a month or nothing at all.

How is IRMAA reduced after a life-changing event?

By requesting a new initial determination on Form SSA-44, supported by evidence, using a more recent tax year. 20 CFR 418.1205 lists seven qualifying events: death of a spouse, marriage, divorce or annulment, stopping work or reducing hours, loss of income-producing property not caused by the beneficiary, cessation or reorganisation of an employer pension plan, and an employer settlement payment.

Form SSA-44 prints eight checkboxes rather than seven because it splits work stoppage and work reduction into separate lines. The categories are otherwise identical to the regulation.

What is not a qualifying event is the part that decides most cases, and 418.1210 is unusually blunt about it. Events other than the seven listed are not considered at all. Beyond that the regulation names two exclusions specifically: events that affect expenses rather than income, and the loss of dividend income through the ordinary risk of investment.

Read against the reasons people actually find themselves in a bracket, that exclusion is wide. A Roth conversion is not a life-changing event. A required minimum distribution is not. A capital gain on a house or a portfolio is not. A one-off consulting payment is not. Each of these can move a household two bands, and none of them opens the door that Form SSA-44 opens. The form is built for a fall in income caused by a listed event, and the reduction must be significant in the regulation's defined sense, meaning it changes the band or removes the surcharge altogether.

What is the deadline for filing Form SSA-44?

There is no 60-day limit on a life-changing event request, despite how often that figure appears. Under 418.1310(a)(4) the request may be made at any time during the calendar year in which the income reduction occurs. Where the event falls in the last three months of a year, the window runs to 31 March of the following year. SSA's own instruction page states no deadline at all.

The 60 days is real, but it belongs somewhere else. It is the window for requesting reconsideration of an initial determination under 20 CFR 404.909(a)(1), which is the formal appeal route, and the two things are not the same procedure. The regulation says so directly at 418.1340: a request for a new initial determination is not a request for reconsideration or further administrative review.

The distinction has teeth. Four separate grounds support a new initial determination under 418.1310(a): supplying the two-year-prior return when the agency used the three-year-prior one, supplying an amended return, proving the IRS information was wrong, and a life-changing event. A request that fits none of them is dismissed, and 418.1310(d) states that the dismissal is not itself subject to further administrative or judicial review.

The trap sits at 418.1330. A beneficiary who files for reconsideration solely because they believe the IRS figure was wrong has their reconsideration dismissed, and is told to obtain proof of the correction from the IRS and request a new initial determination instead. Filing the wrong one of two similarly named things does not merely delay the outcome. It produces a dismissal that cannot be appealed.

Frequently asked questions

Does IRMAA apply every year? It is redetermined annually from a fresh tax year, so a single high-income year produces a single surcharge year. Where a more recent year has been substituted after a life-changing event, 418.1235 ends that substitution once the IRS supplies the relevant data or once the substituted year falls more than three years before the premium year.

Do both spouses pay it? Both pay if both are enrolled. The threshold is tested on joint income, and the surcharge attaches to each enrolled beneficiary separately, so a couple in the first band above $218,000 pays $95.70 twice.

Does an amended return help? It can. Under 418.1150 an amended return may be submitted for a tax year already used, within three calendar years following the close of that tax year, with the retained copy and the IRS confirmation letter or a transcript. Corrections are then made retroactively.

Is Part A affected? No. The surcharge applies to Part B and Part D only. The 2026 Part A inpatient deductible of $1,736 and the Part A premiums paid by the small number of people without enough quarters of coverage are not income-related.

What about immunosuppressive drug coverage? It has its own table and it is subject to the surcharge. The standard 2026 premium for post-transplant immunosuppressive drug coverage under Part B is $121.60, and above the thresholds the total runs from $202.70 to $608.10.

Where do the official figures live? CMS publishes the Part B rates in the Federal Register each November and the Part D surcharge alongside them. SSA republishes both in POMS HI 01101.020, together with the three preceding years, which is the most convenient single place to check a figure for a past premium year.