Picture a retired teacher in Ohio pulling $95,000 a year from her pension and Social Security, comfortably below Medicare’s surcharge threshold. She converts $20,000 from a traditional IRA to a Roth, a routine tax-planning move. Two years later, her monthly Part B premium jumps from $202.90 to $284.10. The notice from the Social Security Administration offers little explanation beyond a acronym she has never encountered: IRMAA.
That stands for Income-Related Monthly Adjustment Amount, and it is Medicare’s way of charging higher-income beneficiaries more for Part B and Part D coverage. The scenario above is hypothetical, but the math is real. An extra $81.20 per month works out to $974.40 over a full year, triggered by a single dollar of income above the threshold. For 2026, that threshold is $109,000 in modified adjusted gross income for individual filers, according to the Centers for Medicare & Medicaid Services’ 2026 Part B fact sheet.
Here is how the surcharge works, who it catches, and what retirees can do before the bill arrives.
How the 2026 IRMAA brackets work
Each fall, the Social Security Administration announces Medicare Part B premiums for the coming year. The standard 2026 Part B premium is $202.90 per month, as published on SSA’s Medicare premiums page. The vast majority of the roughly 67 million Medicare beneficiaries pay that amount and nothing more.
Once your modified adjusted gross income crosses $109,000 as an individual filer, or $218,000 on a joint return, you enter the first IRMAA tier. Your monthly Part B premium rises to $284.10. That increase does not phase in gradually. A retiree reporting $109,001 pays the same surcharge as one reporting $136,000. It functions as a cliff, not a slope.
Additional tiers exist above that first bracket. Premiums climb further at MAGI levels of $137,000, $174,000, $220,000, and above $500,000 for individual filers, with corresponding joint-filer thresholds at roughly double those amounts. But the first tier is where most affected retirees land, because $109,000 in combined retirement income is not unusual for someone collecting a pension, Social Security, investment withdrawals, and required minimum distributions in the same tax year.
One detail that surprises many couples: IRMAA is assessed per person, not per household. If both spouses are on Medicare and the joint return crosses $218,000, each spouse pays the surcharge on their own Part B premium.
The two-year lookback that creates the surprise
IRMAA is not based on your current income. SSA uses IRS data from the tax return filed two years earlier. That means your 2026 premiums are determined by your 2024 modified adjusted gross income. The lag is the single biggest reason retirees are blindsided.
Consider a common pattern: a 64-year-old works a final year with a full salary, collects a severance package, and sells appreciated stock to pay off a mortgage before retiring. Her 2024 MAGI lands at $140,000. She retires in early 2025 and her ongoing income drops to $70,000. When SSA calculates her 2026 Medicare premiums, the agency looks at that $140,000 figure from 2024 and assigns the higher tier. She is paying a surcharge based on income she no longer earns, from money she already spent.
The same trap applies to Roth IRA conversions. The converted amount counts as taxable income in the year of the conversion, even though the entire purpose is to reduce future tax liability. A $30,000 Roth conversion layered on top of $85,000 in other income pushes MAGI to $115,000, clearing the threshold and triggering higher premiums two years down the road.
What counts in MAGI (and what catches people off guard)
For IRMAA purposes, modified adjusted gross income equals your adjusted gross income plus tax-exempt interest income. That second component is the one many retirees overlook. Municipal bond interest is free from federal income tax, but it still counts toward the IRMAA calculation. A retiree who carefully keeps taxable income under $109,000 but collects $15,000 in muni bond interest may find that her MAGI is actually $124,000 for Medicare surcharge purposes.
Other income sources feeding into MAGI include traditional IRA and 401(k) distributions, capital gains from brokerage accounts, rental income, and the taxable portion of Social Security benefits. Qualified Roth IRA withdrawals, by contrast, do not count toward MAGI, provided the account has been open at least five years and the owner is 59½ or older. That exclusion is one reason strategically timed Roth conversions during lower-income years can help retirees stay below the cliff later.
Married couples filing separately face a much steeper version of the problem. The first IRMAA tier for married-filing-separately filers kicks in at just $109,000, the same as for single filers, rather than the $218,000 joint threshold. Couples who file separately for state tax or other reasons should check whether the Medicare cost outweighs the benefit.
Part D carries its own surcharge
IRMAA is not limited to Part B. Under 42 U.S.C. § 1395w-113, Medicare Part D prescription drug plans carry their own income-related surcharge using the identical MAGI thresholds. At the first tier, the Part D add-on is $13.70 per month for 2026, according to CMS. That is smaller than the Part B surcharge, but combined, the two IRMAA charges push total additional Medicare costs above $1,100 a year for an individual who barely clears the income line.
How to appeal when your income has dropped
SSA allows beneficiaries to challenge their IRMAA determination if they have experienced what the agency calls a “life-changing event.” Qualifying events include retirement or a reduction in work hours, marriage, divorce, death of a spouse, and loss of income-producing property. If one of these applies, you can file Form SSA-44 and ask the agency to use a more recent year’s income instead of the standard two-year lookback.
The form is available on SSA’s website and can be submitted at a local Social Security office or by mail. A retiree whose 2024 income was elevated by a final year of employment but whose 2025 or 2026 income falls well below $109,000 can present that evidence and potentially return to the standard premium. SSA does not publish data on approval rates or processing times for these requests, so retirees should expect to continue paying the higher premium until the agency issues a revised determination.
Strategies that can keep you below the cliff
Financial planners who specialize in retirement income often treat MAGI management as a core part of Medicare cost planning. Several approaches can help:
- Spread Roth conversions across multiple years. Instead of converting a large lump sum in one year, convert smaller amounts annually to keep MAGI below $109,000 in each tax year. Because of the two-year lag, you need to plan conversions with the future premium impact in mind.
- Time capital gains carefully. If you plan to sell appreciated investments, weigh whether the gain will push your MAGI over the threshold in a year that will later determine your Medicare premiums.
- Reassess municipal bond holdings. Muni bond income counts toward MAGI for IRMAA purposes. Retirees close to the threshold may need to weigh the federal tax savings of muni bonds against the Medicare surcharge they can trigger.
- Use qualified charitable distributions (QCDs). Retirees age 70½ or older can direct up to $108,000 per year (the 2025 limit, indexed annually for inflation) from a traditional IRA directly to a qualified charity. The distribution satisfies required minimum distribution obligations without adding to MAGI. The IRS has not yet published the 2026 indexed limit.
Each of these strategies involves trade-offs that depend on a retiree’s full financial picture. But the common thread is that IRMAA planning works best when it starts years before the surcharge would take effect, not after the notice arrives in the mailbox.
Why the cliff is wider than most retirees realize
According to the Medicare Trustees’ 2025 annual report, roughly 7% to 8% of Part B enrollees pay some level of IRMAA surcharge. That share has grown as more retirees enter Medicare with 401(k) balances large enough to generate substantial required minimum distributions. The $109,000 threshold is indexed to inflation, but it has not always kept pace with rising retirement account balances or the combination of income streams that today’s retirees juggle.
Congress has the authority to freeze, adjust, or restructure IRMAA brackets in future legislation. No official projection from SSA or CMS confirms where the individual threshold will land for 2027 or beyond, which means retirees building multi-year income plans around the current bracket face the risk that the line shifts in ways that disrupt their strategy.
What the published 2026 figures make plain is this: the gap between the standard Part B premium and the first IRMAA tier is large enough to reshape a retiree’s annual budget. At nearly $1,000 a year in additional Part B costs alone, plus the Part D surcharge on top, crossing $109,000 in MAGI is one of the most expensive single-dollar mistakes a retiree can make. The cliff is documented, it is predictable, and for most people, it is avoidable with planning that starts well before the bill shows up.
David M. Keller is a finance writer based in Columbus, Ohio, covering personal finance and consumer-focused economic topics. He earned his degree in journalism from Ohio University and began his career reporting on local business and economic trends for a regional media outlet. Since then, he has contributed to a variety of online publications, focusing on clear, practical coverage of topics such as cost of living, debt, and everyday financial decision-making.
