The headline number for a 73-year-old annuitant is straightforward. Her contract pays $1,580 a month for life, or $18,960 a year. Less obvious is what that stream does to her Medicare bill once it appears on a tax return alongside Social Security, required minimum distributions, and interest income. In her case, it moved her modified adjusted gross income across two Income-Related Monthly Adjustment Amount thresholds, and her Part B premium reset accordingly.
How Two Brackets Actually Look in 2026
The Centers for Medicare and Medicaid Services set the 2026 standard Part B premium at $202.90 a month for beneficiaries with a modified adjusted gross income of $109,000 or less on an individual return. The surcharge structure adds fixed dollar amounts on top of that base at each higher tier. A single filer with MAGI between $137,000 and $171,000 pays $405.80 per month, which is the second IRMAA tier above the standard rate.
The full 2026 schedule for single filers with standard Part B coverage:
- MAGI at or below $109,000: $202.90
- Above $109,000 through $137,000: $284.10
- Above $137,000 through $171,000: $405.80
- Above $171,000 through $205,000: $527.50
- Above $205,000 through $500,000: $649.20
- At or above $500,000: $689.90
Moving from the standard bracket to the third tier is a $202.90 monthly increase, or $2,434.80 over the calendar year. IRMAA uses a two-year lookback, so 2026 premiums are set from the modified adjusted gross income reported on the 2024 return, which is the return she filed before the annuity payout stream fully counted against her.
Why the Annuity Was the Deciding Line
An annuity of $18,960 a year is not, on its own, a high-income event. Combined with Social Security benefits, taxable withdrawals from an IRA, and interest and dividend income, it can be the marginal dollar that pushes a household from one IRMAA tier to the next. The taxable portion of a non-qualified annuity payment counts in the MAGI calculation, and the surcharges are cliffs rather than gradual phase-ins. One dollar of additional income above $137,000 triggers the full $202.90 surcharge, not a proportional share of it.
Fixed income streams also interact with the annual Social Security cost-of-living adjustment. The 2027 COLA is tracking at 3.1% based on the first month of the Q3 2026 CPI-W window, with the July reading at 327.104. COLA raises Social Security payments in dollars but not the IRMAA thresholds in the same year, so beneficiaries whose non-Social Security income is already close to a cliff can be pushed across it by the very adjustment meant to preserve purchasing power.
The Broader Fixed-Income Backdrop
The strain on retirees living on a fixed monthly check is visible in the national numbers. Per capita disposable personal income climbed to $68,958 in the second quarter of 2026, up from $63,638 in the first quarter of 2024, yet over that same stretch, the personal savings rate cratered from 6.2% to 2.8%. Households have less breathing room for premium increases that show up as a single-line deduction on the Social Security statement.
Consumer prices are hovering near the high end of recent history. The CPI index hit 332.813 in July 2026, up from 323.291 a year earlier, while average annual household expenditures totaled $78,535 in 2024, up from $72,973 in 2022. A guaranteed payment that never changes looks increasingly thin against that backdrop.
What the Case Documents
The annuity paid on schedule, in a fixed amount, for the annuitant’s lifetime. The Medicare bracket measured income two years in arrears, applied a cliff, and produced a higher premium. The two mechanisms interact in a way that is not visible from either contract in isolation. The $2,434.80 in additional Part B premiums for the year reflects the outcome of an income floor meeting an income-tested premium schedule at a threshold, with neither system calibrated against the other to avoid it.
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