The first required minimum distribution generally starts for the year a retiree turns 73, and for many households, that is the moment retirement income becomes harder to control. A person who spent years carefully staying below Medicare’s income surcharge line can cross it almost by accident. It might happen after selling a rental property, taking a year-end Roth conversion, collecting a pension lump sum, or earning a few thousand dollars of municipal bond interest that felt “tax-free” at the time. The problem is that Medicare does not only look at taxable income in the way retirees often expect. It uses a modified adjusted gross income calculation, and once the number crosses the line, the surcharge can show up two years later in the monthly Medicare premium.
That surcharge is called the Income-Related Monthly Adjustment Amount, or IRMAA. It applies to Medicare Part B and Part D premiums for higher-income beneficiaries. CMS has said income-related Part B adjustments affect about 8% of people with Medicare Part B, so this is not something every retiree will face. But the people who do face it are often surprised by how little warning they get. Someone sitting far below the threshold may not need to worry much this year. Someone within $20,000 of the line, or anyone planning a transaction that creates a one-time income spike, should run the numbers before the tax year closes.
The 2026 Line and What Crossing It Costs
For Medicare premiums in 2026, the first IRMAA threshold begins above $109,000 in modified adjusted gross income for single filers and above $218,000 for married couples filing jointly. That line moved up from $106,000 for single filers in 2025 because the brackets are adjusted for inflation. The danger is that IRMAA does not phase in gently at the first tier. Cross the line by even one dollar and Medicare adds $81.20 per month to Part B and $14.50 per month to Part D. Together, that is $95.70 per month per person, or $1,148.40 for the year. For a married couple where both spouses are on Medicare and both are subject to the surcharge, the added annual cost reaches $2,296.80.
Two features make IRMAA feel harsher than the headline number suggests. First, it works like a cliff. A retiree who goes $1 over the income line can owe the same surcharge as someone who goes thousands of dollars over that same line. Second, the surcharge rises sharply as income climbs through higher tiers. At the top 2026 tier, which begins at modified adjusted gross income of $500,000 or more for single filers and $750,000 or more for joint filers, the combined Part B and Part D surcharge reaches $578 per person per month. That means IRMAA is not just a tax planning footnote. It can become a real household budget issue, especially when a one-time financial move affects premiums two years later.
MAGI Counts Things People Forget
For IRMAA purposes, modified adjusted gross income generally starts with adjusted gross income from Form 1040, line 11, then adds tax-exempt interest from line 2a. That second part catches many retirees off guard. Municipal bond interest may be exempt from federal income tax, but it is not invisible for Medicare surcharge purposes. A retiree who shifted part of a portfolio into municipal bonds for “tax-free” cash flow may still see that interest added back when Social Security determines whether IRMAA applies. That is why a household can feel like it made a conservative, tax-smart income move and still end up with a higher Medicare premium.
The lookback also matters. Medicare does not usually base this year’s premium on this year’s income. The 2026 Part B and Part D IRMAA calculation generally reflects income from the 2024 tax return. The 2027 premium will generally reflect 2025 income, and the 2028 premium will generally reflect 2026 income. That delay is what makes IRMAA so frustrating. By the time the notice arrives, the income event may feel like old news. Anything that lifted 2024 MAGI above the line may already be built into a 2026 bill unless a qualifying SSA-44 life-changing event applies. The year retirees can still control right now is calendar 2026, which will generally feed into 2028 Medicare premiums.
The Accidental Triggers
A 67-year-old living mostly on Social Security and modest portfolio withdrawals may never come close to the first IRMAA line. The more common problem happens when several taxable events stack on top of each other in the same year. Required minimum distributions are one of the biggest triggers. RMDs generally begin at age 73, or age 75 for people born in 1960 or later. A retiree with a large traditional IRA can be forced to take taxable income whether the cash is needed or not. For example, a $1.5 million traditional IRA at age 73 could produce a required distribution of roughly $57,000, and that amount can land directly in adjusted gross income.
Roth conversions are another common trigger because the taxable amount converted is included in MAGI for the conversion year. A $50,000 conversion may be a smart long-term tax move, but if it is stacked on top of Social Security, a pension, dividends, and a required distribution, it can easily push a couple above the $218,000 joint threshold. Capital gains can do the same thing. Selling a rental property, downsizing a primary home with gain above the exclusion amount, or rebalancing a taxable brokerage account can all increase AGI. Severance, deferred compensation, pension lump sums, and final-year employment income can also collide with Medicare enrollment in ways retirees do not expect.
The Survivor Trap
The IRMAA problem can become even more painful after the death of a spouse. In the year one spouse dies, the survivor may still be able to file a joint tax return, depending on the circumstances. But many older survivors eventually move from married filing jointly to filing as single. That change matters because the single IRMAA brackets are roughly half the joint brackets. A couple that had income comfortably below the $218,000 joint threshold may not look nearly as comfortable when one person is left filing under a single threshold of $109,000. The survivor’s income may fall, but often not by half.
This is especially difficult because several expenses may remain the same even after one spouse dies. Housing costs, property taxes, utilities, insurance, and vehicle expenses may not decline enough to offset the change in tax filing status. Pension income may drop, but Social Security survivor benefits, investment income, taxable account distributions, and required minimum distributions can still keep the surviving spouse near or above the single IRMAA line. Nothing about the survivor’s lifestyle may feel wealthier. The bracket simply changed. That is why widows and widowers need to revisit Medicare premium planning, withdrawal strategy, and tax projections after a spouse dies instead of assuming last year’s household income plan still works.
What SSA-44 Can and Cannot Fix
Form SSA-44 can help when a Medicare beneficiary’s income has dropped because of a qualifying life-changing event. Social Security lists events such as marriage, divorce or annulment, death of a spouse, work stoppage, work reduction, loss of income-producing property, loss of pension income, and certain employer settlement payments. When one of those events applies, the beneficiary can ask Social Security to use a more recent, lower income estimate instead of the older tax return that would normally drive IRMAA. This can be especially important for someone who recently retired, reduced work hours, lost a pension, or became widowed.
But SSA-44 is not a cure-all for every income spike. It generally does not reverse voluntary income events simply because the result was expensive. A Roth conversion, voluntary sale of appreciated property, large taxable brokerage gain, or planned IRA withdrawal usually will not qualify just because it pushed MAGI over the line. That does not mean the surcharge lasts forever. IRMAA is recalculated each year based on the applicable tax return. But it does mean retirees should not assume they can appeal their way out of a self-created income spike. The better approach is to model the surcharge before creating the income, then decide whether the tax move is still worth it after Medicare costs are included.
What to Do This Year
The first step is to model the IRMAA line before December, not after the return is filed. Add projected adjusted gross income and tax-exempt interest, then compare the total with the 2026 thresholds of $109,000 for single filers and $218,000 for joint filers. Anyone within about $20,000 of the line should be careful with discretionary income events. That includes Roth conversions, taxable account rebalancing, mutual fund capital gain distributions, rental property sales, pension lump sums, and extra IRA withdrawals. If the income is controllable, it may be possible to defer part of it, split it across two tax years, or schedule it in a year with more room.
Retirees who give to charity should also look at Qualified Charitable Distributions once they qualify. QCDs are available beginning at age 70½ and can allow money to move directly from an IRA to a qualified charity. When handled properly, the distribution can count toward an RMD but stay out of adjusted gross income. For retirees who already donate, that can be one of the cleanest ways to keep IRA dollars from increasing MAGI. Finally, anyone who has a qualifying life-changing event should file SSA-44 promptly instead of waiting for the two-year lookback to correct itself. Retirement, work reduction, and the death of a spouse may support a request when documentation shows both the event and the lower expected income.
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The Line Is Easier to Avoid Before You Cross It
IRMAA is not a reason to avoid every Roth conversion, asset sale, RMD strategy, or portfolio rebalance. Sometimes paying the surcharge may still be worth it if the bigger financial move saves more in taxes or improves the long-term plan. The mistake is treating Medicare premiums as separate from tax planning. A few thousand dollars of extra MAGI can turn into a full year of higher Part B and Part D premiums, and for married couples, the cost can double when both spouses are on Medicare. That can change the true price of a conversion, sale, or withdrawal.
The key is timing. Before the tax year closes, retirees still have options. They may be able to reduce a conversion, harvest losses, delay a gain, use a QCD, reconsider a year-end distribution, or prepare documentation for an SSA-44 request if a qualifying event applies. After the return is filed and the two-year lookback reaches it, there may be little to do except pay the higher premium and plan better for the next year. The IRMAA line is not always obvious, but it is usually easier to avoid before crossing it than to fix after the bill arrives.
Sources: CMS, “2026 Medicare Parts A & B Premiums and Deductibles”; SSA Form SSA-44 and SSA IRMAA guidance; IRS guidance on required minimum distributions and Qualified Charitable Distributions. Figures reflect 2026 plan-year rules.
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