Medicare Surcharges Spike $1,062 a Year at the $109,000 Income Threshold Most Retirees Miss

The Quiet Cliff Sitting Between $108,999 and $109,001

A single retiree, age 70, lives off Social Security, a modest pension, and a traditional IRA. Her required minimum distribution just kicked up. She runs the numbers in April and realizes her modified adjusted gross income for the year came in at $109,400. She is $400 over a line she did not know existed, and that $400 will cost her roughly $1,062 in extra Medicare premiums next year.

This is the Income-Related Monthly Adjustment Amount, or IRMAA. One dollar over the threshold triggers the full surcharge. There is no phase-in, no gradual ramp. A retiree on a fixed budget can lose more than a thousand dollars because a dividend reinvested on December 30 pushed her over.

A widower did a $20,000 Roth conversion in November, only to discover in February that the conversion bumped him $1,800 past the threshold and into a higher Part B bracket. He called it the most expensive paperwork mistake of his retirement.

What Actually Drives the Outcome

For 2026, the first IRMAA tier triggers at $109,000 of MAGI for single filers and $218,000 for married filing jointly, based on the tax return filed two years earlier. So the 2026 surcharge is calculated from 2024 income. That two-year lookback catches retirees off guard, especially anyone who sold a house, took a large IRA distribution, or did a Roth conversion that year.

Crossing the line by even one dollar adds $74 per month to Part B and $14.50 per month to Part D. That works out to $88.50 a month, or $1,062 a year. At $108,999 MAGI, the standard Part B premium is $202.90 per month. At $109,001, it jumps to $276.90, the same Medicare coverage costs $74 more per month, or at least until next year’s income recalculation.

MAGI for IRMAA goes beyond the number on the bottom of the 1040. It equals adjusted gross income plus tax-exempt municipal bond interest plus the non-taxable portion of Social Security. Traditional IRA distributions, capital gains, dividends, interest, and the taxable portion of Social Security all count. Roth IRA withdrawals, qualified HSA distributions for medical expenses, and the return-of-basis portion of annuity payments do not.

Where the Levers Are

For a single retiree hovering near $109,000, three moves do most of the work:

1. Roth conversions before Medicare eligibility. The years between retirement and age 63 are the sweet spot. Conversions done at 63 or later show up on the return that determines IRMAA two years out. Filling up the 12% or 22% bracket in your early 60s can shrink future RMDs enough to keep you below the cliff for the rest of retirement.
2. Qualified charitable distributions after 70.5. A QCD sends money directly from a traditional IRA to a charity and counts toward the RMD without hitting MAGI. The 2026 limit is roughly $108,000 per person, which is more than enough headroom for almost anyone trying to duck under the threshold.
3. Tax-loss harvesting in heavy capital gains years. Selling losers to offset realized gains can be the difference between $108,500 and $110,000 of MAGI. In a year with mutual fund distributions or a large rebalance, this matters.

How It Fits the Bigger Picture

IRMAA is rarely the largest line item in a retirement plan, but it is one of the most controllable. Inflation makes the threshold problem worse over time. The Consumer Price Index sat at 332.4 in April 2026, up from 320.6 a year earlier, and IRMAA brackets adjust slowly. Meanwhile, per capita disposable income has climbed from $63,638 in early 2024 to $68,617 in the first quarter of 2026, pulling more retirees toward the line each year.

A traditional IRA that has compounded for decades produces RMDs that grow every year as the divisor shrinks. Add Social Security, a pension, and a few thousand in dividends from a taxable brokerage, and a retiree who felt comfortably middle-class suddenly finds herself a few hundred dollars into surcharge territory.

What to Think Through Before December 31

The mistake that is hardest to undo is realizing income you did not need to realize. Once a Roth conversion is processed or an IRA distribution is taken, it is on the return. The fix has to happen before year-end, which means running a projected MAGI in October or November, not in April when the 1099s arrive.

If you are within a few thousand dollars of $109,000, the last $1,000 of income in December is the most expensive money you will earn all year. A QCD, a small loss harvest, or deferring a discretionary IRA withdrawal to January can save more than $1,000 in Medicare premiums. The planning window that matters most is your early 60s, before the two-year IRMAA lookback starts catching your conversions. Decisions made at 61 quietly shape premiums at 65.

The threshold is unforgiving, but it is predictable, which means it rewards anyone willing to spend an afternoon with last year’s tax return and a calculator.