A Six-Figure Public Pension Feels Like a Reward. It Can Also Quietly Push a Retiree Into Medicare’s IRMAA Surcharge.

Picture a recently retired teacher, police lieutenant, or state agency director. Thirty-plus years of service, a defined-benefit pension paying roughly $100,000 a year, and a modest Social Security benefit. The pension check arrives every month, indexed for inflation, guaranteed for life. Then the first Medicare bill lands, and the Part B premium is hundreds of dollars higher than the standard amount. Welcome to the Income-Related Monthly Adjustment Amount, or IRMAA, the surcharge Medicare tacks on when your income crosses certain thresholds.

One retiree on a public-employee forum described opening the notice and thinking the government had made a mistake, only to learn the charge was correct. Every dollar of the pension counts as ordinary income, flowing into Modified Adjusted Gross Income (MAGI), which is what Medicare uses to decide whether you pay the base premium or a surcharge.

Why the IRMAA cliff matters more than the tax bracket

In 2026, a single filer with MAGI at or below $109,000 (or a joint filer at or below $218,000) pays the standard Part B premium of $202.90 per month and no Part D surcharge. Cross that first line by even a dollar and the Part B premium jumps by $81.20 a month, with an added $14.50 on Part D.

Cross the next tier (single MAGI above $137,000 or joint above $274,000) and the Part B surcharge climbs to $202.90 per month on top of the base premium, with Part D adding $37.50. For a married couple where both spouses hit the tier, that is a real four-figure annual hit for stepping just over a line.

Three details make this worse than most retirees expect. First, the brackets are cliffs, not phase-ins. One dollar over is the full surcharge.

Second, the IRMAA thresholds have been essentially frozen since 2003, while pensions, Social Security, and asset income keep drifting up. The Consumer Price Index for All Urban Consumers (CPI-U), the broad measure of what Americans pay for goods and services, climbed from 322.169 in July 2025 to 335.123 in May 2026, confirming that prices are rising faster than the Medicare income thresholds are moving. The 2026 Social Security COLA came in at 2.8%. Benefits go up. The thresholds do not. More retirees get pulled in each year without any real gain in purchasing power.

Third: Medicare uses a two-year lookback. Your 2026 premium is based on the MAGI reported on your 2024 tax return. A pension that started, a Roth conversion you did, or a house you sold two years ago is what prices your Medicare today.

The Social Security tax squeeze underneath

A six-figure pension lifts your provisional income high enough that up to 85% of your Social Security benefit becomes federally taxable. Those provisional income thresholds ($25,000 and $34,000 for singles, $32,000 and $44,000 for joint filers) have been frozen since 1984. Anyone drawing a pension of that size will almost certainly see the maximum share of their Social Security taxed. If your monthly benefit is $2,000, roughly $1,700 of it lands in taxable income each month, taxed at your marginal rate.

Combine the IRMAA surcharge with the Social Security tax and the pension’s true after-cost value is meaningfully lower than the gross number suggests.

How the pieces connect

The pension is fixed. You cannot dial it down. But other MAGI levers are within your control:

1. Roth versus traditional withdrawals. Money pulled from a Roth IRA does not count toward MAGI. Traditional IRA and 401(k) withdrawals do. Sequencing matters when you are close to a bracket line.
2. Capital gains timing. Realizing a big gain in the same year you are already near an IRMAA threshold can push you across two tiers at once.
3. Qualified charitable distributions. Starting at age 70½, giving directly from an IRA to charity satisfies required minimum distributions without adding to MAGI.
4. Form SSA-44. If a life-changing event (retirement, a spouse’s death, divorce) has dropped your income, you can ask Social Security to use current income instead of the two-year-old return.

What to think through before the first premium notice

The mistake that is hardest to undo is not planning for IRMAA before retirement. Once the pension starts and the tax return is filed, the two-year lookback locks in your premium. You cannot appeal a surcharge just because it feels unfair.

A six-figure pension is a genuine gift, and the surcharge does not erase it. What it does is reward retirees who look at the whole picture before pulling levers. Model your MAGI a year or two out, know where the next tier begins, and treat every Roth conversion, gain harvest, or one-time withdrawal as a decision that touches Medicare, not just taxes. A short session with a tax professional who understands both IRMAA and provisional income can pay for itself many times over.

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