IRMAA: The Medicare Income Surcharge

What IRMAA is

IRMAA stands for income-related monthly adjustment amount. It is an addition to the standard Medicare Part B and Part D premiums, charged to beneficiaries whose income exceeds a statutory threshold. It is authorized by sections 1839(i) and 1860D-13(i) of the Social Security Act, implemented at 20 CFR 418.1115 and 418.2115, and administered by the Social Security Administration rather than by Medicare.

The framing matters for understanding why it behaves the way it does. Medicare Part B is heavily subsidized - most beneficiaries pay roughly a quarter of the program's actual per-person cost, with general revenues covering the rest. IRMAA is not a tax on income in any technical sense. It is a reduction in that subsidy for higher-income beneficiaries, collected in the form of a higher premium. That is why it is a set of fixed dollar amounts rather than a percentage of income, and why it stops rising at the top bracket: once the subsidy is fully withdrawn, there is nothing further to remove.

CMS reports that IRMAA affects roughly 8 percent of people with Part B and a similar share of those with Part D. It is a minority experience, which is part of why it catches so many people unprepared - most retirees have never heard of it until the determination letter arrives.

The two-year lookback

This is the mechanic that causes most of the surprise. Your Medicare premium for a given year is based on the income you reported two years earlier.

Per SSA POMS HI 01101.010, the MAGI used is "the most recent tax information that IRS is able to provide," which is generally from two years prior to the premium year, but not more than three years prior. So:

• 2026 premiums are based on the 2024 tax return, filed in 2025.
• If no 2024 return is on file when the determination is made, SSA falls back to 2023.
• 2027 premiums will be based on 2025, and so on.

Three consequences follow, and each one trips people up:

First, the money is already spent. A decision made in 2024 - selling a rental, converting an IRA, taking a large distribution - produces a bill in 2026, by which time the proceeds have usually been deployed. There is no reserve set aside because nobody knew to set one aside.

Second, planning starts before you enroll. Most people enroll in Medicare at 65. The income that sets that first premium was earned at 63. If you are approaching Medicare and still working, or planning a large transaction, the relevant question is not what your income will be when you enroll but what it is right now.

Third, it fixes itself. Because the determination is redone annually against a fresh year, a surcharge triggered by one unusual year falls away on its own once that year rolls out of the window - typically after twelve months. No form, no appeal, no action needed. Understanding this prevents a good deal of unnecessary panic: a one-year surcharge is a one-year problem.

What counts as MAGI

MAGI is one of the most overloaded terms in the tax code - the premium tax credit, Roth IRA eligibility, and IRMAA all use different definitions. For IRMAA the definition is unusually simple and unusually narrow. Per SSA POMS HI 01101.010, MAGI is:

• Adjusted gross income, from line 11 of Form 1040, plus
• Tax-exempt interest income, from line 2a of Form 1040.

That is the entire calculation. Unlike other MAGI definitions, there is no add-back for the foreign earned income exclusion, student loan interest, IRA contributions, or excluded savings bond interest.

The item that catches people is the second one. Tax-exempt municipal bond interest counts in full. Retirees frequently hold munis specifically because the interest escapes federal income tax, and are then startled to find that same interest raising their Medicare premiums. Municipal bonds reduce your tax bill but do nothing for your IRMAA bracket.

Because MAGI starts from AGI, everything that lands in AGI feeds it: wages, self-employment income, taxable Social Security benefits, pension and annuity income, required minimum distributions, Roth conversion amounts, capital gains, dividends, interest, and rental income. Notably, qualified Roth distributions do not, because they never enter AGI - which is the entire strategic case for Roth assets in retirement. Our MAGI guide compares the competing definitions side by side, and the AGI Calculator helps you build the starting figure.

The 2026 IRMAA brackets

CMS published the 2026 amounts on November 14, 2025. The standard Part B premium is $202.90 a month, up from $185.00 in 2025, and the annual Part B deductible is $283.

The thresholds are indexed annually. For reference, the first-tier threshold has moved as follows: $97,000 (2023), $103,000 (2024), $106,000 (2025), and $109,000 (2026) for single filers, with the joint threshold at exactly double each year.

Why IRMAA is a cliff, not a phase-in

Most of the tax code phases things in. Deductions taper, credits reduce gradually, and brackets apply only to the income above each threshold. IRMAA does none of this. It is a pure step function.

If your MAGI exceeds a threshold by one dollar, you pay the entire surcharge for that bracket, for all twelve months. There is no proration, no blending, and no partial application. The marginal cost of that dollar is the full annual step:

Read the second row carefully. A single dollar of additional income, recognized at the wrong moment, can cost $1,736.40. For a couple where both spouses are enrolled, the same dollar costs $3,472.80.

This produces effective marginal rates that are, briefly, absurd. A retiree who takes one extra dollar of IRA distribution at exactly the wrong point faces a marginal cost of over 170,000 percent on that dollar. The number is a curiosity rather than a planning input, but the underlying point is serious: near a threshold, the ordinary logic of "a bit more income is a bit more tax" fails completely.

The practical implication is that the last dollar of the year is the one that matters. Income recognized in December, when the year's total is nearly known, can be evaluated precisely against the threshold. Income recognized in January cannot. This asymmetry is why year-end IRMAA checks are worth doing and why our IRMAA Calculator reports remaining headroom as a headline figure.

Why married couples pay twice

IRMAA attaches to the beneficiary, not to the tax return. A married couple filing jointly report a single MAGI figure, that figure determines a single bracket, and then each enrolled spouse pays the full surcharge for that bracket.

The arithmetic is straightforward and unwelcome. A couple with $280,000 of 2024 MAGI, both on Part B and Part D, sit in tier 2. Each pays $202.90 in surcharge for Part B and $37.50 for Part D, so the household pays $480.80 a month in surcharge - $5,769.60 a year - on top of two standard premiums.

Two implications follow. First, every threshold calculation for a couple should be done at double the per-person figures; a $1,736.40 step is really a $3,472.80 step. Second, timing matters around the enrollment of the second spouse. If one spouse turns 65 two years after the other, a high-income year affects only one of them at first, then both once the younger spouse enrolls. Couples with an age gap sometimes find their Medicare costs jump sharply in a year when nothing about their income changed at all.

The Part D surcharge

The Part D IRMAA works slightly differently from the Part B version, and the difference causes confusion.

There is no "standard" Part D premium set by the government. Part D is delivered by private plans, each of which sets its own premium. The IRMAA surcharge is therefore added on top of whatever your plan charges, and it ranges from $14.50 to $91.00 a month for 2026.

Critically, the surcharge is not paid to your plan. It goes to Medicare, either deducted from your Social Security check or billed separately. This means:

• You will pay a Part D IRMAA even if you chose a $0-premium plan. The surcharge exists independently of the plan premium.
• You will pay it if your drug coverage comes through a Medicare Advantage plan that includes Part D.
• You receive a separate bill or deduction for it, which is why some beneficiaries believe they are being charged twice. They are not - one payment is the plan's premium, the other is the government's surcharge.

Dropping Part D to avoid the surcharge is almost always a mistake: doing so exposes you to the Part D late-enrollment penalty, which is permanent and grows the longer you go without creditable coverage.

Appealing with Form SSA-44

If your income has fallen since the year SSA used, you can request a new initial determination using Form SSA-44, asking SSA to base your premium on a more recent year's estimated income instead.

This is available only if a qualifying life-changing event caused the reduction. Per SSA POMS HI 01120.005, there are exactly eight:

1. Death of a spouse
2. Marriage
3. Divorce or annulment
4. Work reduction
5. Work stoppage (including retirement)
6. Loss of income-producing property
7. Loss of an employer pension
8. Receipt of a settlement payment from a current or former employer

SSA's guidance is explicit that this list is exclusive. The reduction must also be "significant," meaning large enough to decrease or eliminate the surcharge.

The process is more forgiving than most people expect. You attest under penalty of perjury that the event occurred and caused the income reduction, and SSA accepts that statement - the agency does not develop the individual income components, only that MAGI decreased and that the event preceded the decrease. Bring documentation of the event itself (a death certificate, a letter from an employer, a marriage certificate) and your estimate of current-year income.

The most common successful case is straightforward retirement. Someone who worked through 2024 at a high salary and retired in 2025 will be assessed in 2026 on their final working year, and work stoppage lets them replace that with their actual retirement income. This single form routinely saves several thousand dollars.

One limitation worth knowing: a granted request applies only to the person reporting it. If an event affects a spouse or ex-spouse, SSA does not extend the finding to the non-reporting person, who must file their own request.

What cannot be appealed

This section exists because the misconception is so widespread and so expensive.

A one-time increase in income is not a life-changing event. SSA treats it as a non-qualifying event, explicitly. The logic is consistent, even if it feels unfair: the eight qualifying events are all things that reduce your ongoing income. A transaction that temporarily raised your income is not among them, no matter how obviously non-recurring it was.

So none of the following supports an appeal:

• A Roth conversion, however strategically sound
• The sale of a home, business, or investment property
• A large capital gain or year-end mutual fund distribution
• An unusually large required minimum distribution
• Exercising stock options or vesting of restricted stock
• An inherited IRA distribution

SSA also lists reductions that do not qualify even though they lower income: an ordinary loss of dividend income, higher medical or living expenses, loss of child support or alimony, and the voluntary sale of income-producing property. Note the contrast in that last one - losing income-producing property (through a disaster or a criminal act, for instance) qualifies; choosing to sell it does not.

The remedy for a one-time spike is not an appeal. It is the calendar. The surcharge applies for one year and then disappears when a normal income year replaces the unusual one. Knowing this converts an infuriating problem into a budgeting exercise.

Managing your brackets

Because IRMAA is mechanical, it is also predictable - and predictable costs can be planned around. Every effective strategy works on the income two years ahead, not on the surcharge itself.

Size Roth conversions to the threshold. Conversions are the most common self-inflicted IRMAA event and also the most controllable, because you choose the amount. Compute the headroom to the next bracket and convert up to it, not past it. Converting $9,000 rather than $15,000 to stay under a line is frequently worth more than the tax arbitrage of converting the extra $6,000. Model this with the Roth Conversion Tax Calculator alongside the IRMAA figures.

Use qualified charitable distributions. A QCD from an IRA satisfies your required minimum distribution without the distribution entering AGI at all. For a charitably inclined retiree whose RMDs are pushing them over a threshold, this is the single cleanest tool available - it reduces IRMAA MAGI in a way that an ordinary distribution followed by a charitable deduction does not, because the deduction reduces taxable income but never touches AGI.

Spread gains across years. Installment sales, staged liquidation of a concentrated position, and simple calendar timing all convert one bracket-breaking year into two ordinary ones.

Watch tax-exempt interest. Municipal bonds do not help here. If you are near a threshold and holding munis for tax efficiency, be aware that the interest counts in full for IRMAA even while it escapes income tax.

Front-load before 63. Because of the lookback, income recognized before the year you turn 63 never touches Medicare premiums. Large planned conversions are cheapest well before Medicare age.

Check in December. The single highest-value habit is a year-end review of year-to-date MAGI against the next threshold, before executing any discretionary transaction. Everything above depends on knowing the headroom number.

What does not work: filing separately (usually far worse, see the bracket tables), dropping Part D (triggers a permanent late-enrollment penalty), or refusing Part B while otherwise eligible (also triggers a permanent penalty and can leave you uninsured).

How IRMAA is billed

How you pay depends on whether you are collecting Social Security.

If you receive Social Security benefits, the Part B premium including any surcharge is deducted directly from your monthly benefit, as is the Part D surcharge. The deduction happens automatically, which is why many people first notice IRMAA as an unexplained drop in their deposit.

If you are not yet collecting, Medicare bills you directly for Part B, quarterly by default. The Part D surcharge is billed separately by Medicare rather than added to what you pay your plan.

SSA notifies you of a determination by mail in the autumn preceding the premium year, in a notice titled an Initial IRMAA Determination. Read it when it arrives: it states the tax year used and the MAGI figure SSA relied on. If either is wrong - a common cause is an amended return the IRS has not yet transmitted - that is a factual error to raise with SSA immediately, and it is a different process from the life-changing-event request.

One important interaction: the hold-harmless provision, which prevents a Part B premium increase from exceeding a beneficiary's Social Security cost-of-living increase, does not apply to IRMAA. Beneficiaries subject to the surcharge are not protected by it.

Common mistakes

• Assuming a bad year can be appealed. It cannot, unless it was caused by one of the eight events. This is the costliest misconception in the entire topic.
• Treating the threshold as a phase-in. Going $100 over is not "a little" IRMAA. It is all of it.
• Forgetting the second spouse. Doubling applies to the surcharge, so a couple's exposure at every threshold is twice the published figure.
• Ignoring tax-exempt interest. Munis reduce taxable income but not IRMAA MAGI.
• Planning from age 65 instead of 63. The lookback means Medicare-relevant planning begins two years before enrollment.
• Converting to a Roth without checking the bracket. The conversion tax is visible and immediate; the IRMAA consequence is invisible for two years.
• Filing separately to reduce income. For a couple who lived together, this usually multiplies the surcharge rather than reducing it.
• Panicking over a one-year surcharge. It resolves itself. Budget for it and move on.

Frequently asked questions