The $109,000 Threshold That Triggers Medicare Surcharges Most Retirees Miss

Most Medicare enrollees pay the same $202.90 per month for Part B coverage. But cross one of five critical income lines and that number jumps, sometimes by hundreds of dollars, for the entire year. The surcharge is called IRMAA (Income-Related Monthly Adjustment Amount), and for many, the shock is compounded by a 2026 Part B deductible that has climbed to $283.

The Five Income Thresholds

IRMAA is based on your Modified Adjusted Gross Income (MAGI) from two years prior. For 2026, that means your 2024 tax return determines which tier applies. The five thresholds work like cliff edges: one dollar over the line moves you into the next bracket for the full year. Unlike standard tax brackets, crossing these lines also strips away “Hold Harmless” protections, meaning a surcharge could actually shrink your net Social Security check.

1. Tier 1 (single: $109,001–$137,000 / joint: $218,001–$274,000): Part B rises to $284.10/month, plus a $14.50/month Part D surcharge. Annual extra cost: roughly $1,114 more per year.
2. Tier 2 (single: $137,001–$171,000 / joint: $274,001–$342,000): Part B jumps to $405.80/month, with a $37.40/month Part D add-on. Annual extra: $2,956.
3. Tier 3 (single: $171,001–$205,000 / joint: $342,001–$410,000): Part B reaches $527.50/month and Part D adds $60.20/month. Annual extra: $4,738.
4. Tier 4 (single: $205,001–$500,000 / joint: $410,001–$750,000): Part B hits $649.20/month. Annual extra: $6,520.
5. Tier 5 (single: above $500,000 / joint: above $750,000): Part B reaches $689.90/month, with a $91.00/month Part D surcharge. Annual extra: $6,927.

Why Retirees Get Caught Off Guard

The entry threshold has sat at or near $109,000 for single filers while incomes have risen steadily. Per capita disposable personal income reached $67,648 in late 2025. While Social Security saw a 2.5% COLA for 2026, early projections for the 2027 COLA are already trending higher, between 2.8% and 3.2%, which may push even more retirees toward the “cliff” next year.

Interest income remains a primary culprit. With the federal funds rate currently hovering around 3.63%, retirees holding CDs and high-yield savings accounts are generating significant taxable interest. This income counts toward your MAGI and can unexpectedly trigger a Tier 1 or Tier 2 jump.

Six Ways to Stay Below the Next Cliff

1. Size Roth conversions carefully. Converting just enough to stay below the next tier captures tax-free growth without triggering a surcharge jump.
2. Spread capital gains across years. Selling appreciated assets over two or three years instead of one keeps any single year’s MAGI lower.
3. Harvest capital losses. Losses in taxable accounts offset gains dollar for dollar, reducing MAGI before year-end.
4. Maximize Qualified Charitable Distributions (QCDs). For 2026, the IRS has increased the QCD limit to $111,000. Retirees 70.5 and older can send this amount directly from an IRA to charity to keep it entirely off their MAGI.
5. Claim the New Above-the-Line Deduction. If you don’t itemize, a new 2026 rule allows a deduction of up to $1,000 ($2,000 for joint filers) for cash donations, providing a simple way to shave a few hundred dollars off your MAGI.
6. File SSA-44 after a life-changing event. If income dropped due to retirement, divorce, or a spouse’s death, the SSA-44 form lets you appeal to use a more recent year’s income instead of the two-year lookback.

The toughest mistake to undo is discovering the surcharge after the year closes. Income planning works best in the fall, when you still have time to control distributions before December 31st. A tax professional can help model the scenarios before it’s too late.