A retired teacher in suburban Ohio who reported $108,900 of modified adjusted gross income on her 2024 tax return will pay $202.90 a month for Medicare Part B in 2026. Her former colleague down the street, who reported $109,100 after a modest Roth IRA conversion, will pay $284.10. That $200 gap in annual income triggers an $81.20 monthly surcharge on Part B alone, adding $974.40 to the year’s Medicare bill. There is no gradual phase-in, no partial step, and no rounding in the beneficiary’s favor.
The mechanism responsible is called the income-related monthly adjustment amount, or IRMAA. It operates on a cliff structure: stay one dollar below the threshold and you pay the standard premium; cross it by one dollar and you pay the full surcharge for that bracket. (The headline references $74.40, which reflects the additional monthly cost that IRMAA adds to Part D prescription drug premiums at the same first income tier. Combined, the first IRMAA cliff raises total monthly Medicare costs by more than $150.)
What sharpens the impact is timing. The Social Security Administration does not look at 2026 earnings to set 2026 premiums. It reaches back two years, pulling your MAGI from the 2024 federal tax return you filed in early 2025. A Roth conversion, a stock sale, or a larger-than-usual distribution from a traditional IRA during 2024 is already locked in. There is no way to undo it now.
The 2026 brackets, confirmed by CMS
The CMS fact sheet for 2026 sets the standard Part B premium at $202.90 per month. Single filers with MAGI at or below $109,000, and married couples filing jointly at or below $218,000, pay that base rate. Cross the first threshold by even one dollar, and the full IRMAA surcharge applies.
Here is how the single-filer brackets break down for 2026:
- $109,000 or less: $202.90/month (standard premium, no surcharge)
- $109,001 to $137,000: $284.10/month ($81.20 surcharge)
- $137,001 to $171,000: $402.90/month ($200.00 surcharge)
- $171,001 to $214,000: $521.80/month ($318.90 surcharge)
- $214,001 to $500,000: $640.60/month ($437.70 surcharge)
- Above $500,000: $678.80/month ($475.90 surcharge)
Married couples filing separately face a compressed bracket structure with much lower thresholds. Those with MAGI above $109,000 jump directly to higher surcharge tiers, a detail that catches some recently divorced or widowed beneficiaries off guard.
The legal authority for these adjustments comes from Social Security Act Section 1839, which directs CMS to calculate income-related premium increases each year. Implementing regulations under 20 CFR Section 418.1001 govern how SSA applies the adjustments, and the 2026 Federal Register notice formalizes the thresholds and dollar amounts.
Why the two-year lookback catches people off guard
SSA’s process is straightforward but unforgiving. To calculate your 2026 IRMAA, the agency requests your most recent tax data from the IRS. For a determination taking effect in January 2026, that means your 2024 return. The SSA Medicare premiums page confirms that higher-income beneficiaries pay more based on this income review.
The two-year lag is where confusion takes root. Consider a retiree who was comfortably below $109,000 in 2023 but converted $25,000 from a traditional IRA to a Roth during 2024, pushing MAGI to $112,000. That conversion did not affect 2025 premiums, which were based on the 2023 return. It hits in 2026, well after the conversion is complete and the tax bill is paid. By the time SSA mails its initial determination notice in late 2025, the retiree has no opportunity to reverse the transaction.
One detail that trips up retirees who hold municipal bonds: MAGI for IRMAA purposes is your adjusted gross income plus tax-exempt interest income. Interest from munis that is excluded from federal income tax still counts toward the IRMAA calculation. “Tax-free” does not mean invisible to Medicare.
How to request a lower premium after a life-changing event
SSA does offer a path for beneficiaries whose financial picture changed significantly after the lookback year. If you experienced a qualifying life-changing event, such as retirement, a reduction in work hours, the death of a spouse, divorce, or the loss of income-producing property, you can ask SSA to use a more recent year’s income instead.
The form for this request is SSA-44, titled “Medicare Income-Related Monthly Adjustment Amount, Life-Changing Event.” You can file it at your local Social Security office or by mail, along with documentation of the event and evidence of your reduced income. The option is worth pursuing for anyone who qualifies, because the savings can run into thousands of dollars over a single year.
One firm limitation: general market losses or a bad investment year do not count as qualifying events. The list is specific and codified in regulation, and SSA adjudicates each request individually.
The planning window that already closed, and the one still open
Financial planners who work with Medicare-age clients tend to zero in on the $95,000 to $115,000 MAGI range for single filers, where small decisions about Roth conversions, capital gains harvesting, and required minimum distributions can push someone across the $109,000 line. For 2026 premiums, that planning window was calendar year 2024, and it is shut.
What remains open is the 2025 tax year, which will determine 2027 IRMAA. Retirees who landed above the threshold for 2024 may want to work with a tax professional now to model whether spreading conversions over multiple years, timing asset sales, or adjusting withholding on RMDs could keep 2025 MAGI below the cliff. The math varies by household, but the underlying principle holds: every dollar of MAGI above $109,000 costs the same $81.20 per month as a dollar $28,000 above it, until you reach the next bracket at $137,000.
Part D prescription drug coverage carries its own IRMAA surcharges at the same income thresholds, compounding the cost. At the first tier ($109,001 to $137,000 for single filers), Part D IRMAA adds roughly $74.40 per month on top of whatever plan-specific premium the beneficiary already pays. Combined with the Part B surcharge, a retiree just over the first cliff faces more than $1,800 in additional annual Medicare costs.
These surcharges apply whether you are enrolled in Original Medicare or a Medicare Advantage plan. IRMAA is tied to Part B and Part D, not to the delivery system, so switching to an Advantage plan does not eliminate the extra cost.
How to check your notice and what comes next
SSA mails initial IRMAA determination notices to affected beneficiaries before coverage begins. Those letters show the income figure SSA pulled from the IRS, the bracket it falls into, and the resulting monthly premium. Retirees should review the notice line by line. If the income figure is wrong, perhaps because of an amended 2024 return that the IRS had not yet processed, the beneficiary can contact SSA to request a correction.
For those whose 2024 income is accurately reported and simply higher than expected, the surcharge stands unless a qualifying life-changing event applies. The cliff structure means there is no negotiation, no hardship waiver, and no partial credit for landing close to the line. Congress built IRMAA as a bright-line test, not a sliding scale.
Whether that design serves retirees well is a policy question that remains unresolved. Advocacy organizations, including some within the Medicare rights space, have periodically called for smoothing the cliffs into a gradual slope, which would reduce the penalty for small income overages but spread costs more broadly. As of May 2026, no legislation to restructure IRMAA brackets has advanced beyond committee in Congress, and the current cliff framework remains the law that beneficiaries must plan around.
