Overview
- IRMAA bases Medicare surcharges on modified adjusted gross income from the tax return filed two years earlier, so a big withdrawal today can raise your Medicare Part B and Part D premiums two years later.
- A $2.5 million traditional 401(k) produces an age‑73 RMD of about $94,340 under the IRS Uniform Lifetime Table, and that forced taxable income can push couples into higher tax brackets and IRMAA tiers.
- CMS set the 2026 Part B base premium at $202.90 and IRMAA‑adjusted Part B premiums range from $284.10 to $689.90 per person depending on MAGI, with cliffed thresholds that trigger the full surcharge if crossed by even one dollar.
- Advisers say the main ways to reduce long‑term exposure are annual Roth conversions timed to fill low tax brackets, qualified charitable distributions to satisfy RMDs without adding to MAGI, and other bracket‑smoothing moves done before the first RMD hits.
- The policy backdrop makes this urgent because SECURE 2.0 set age‑73 as the default RMD start for many people in 2026, narrowing the window for cost‑saving moves and meaning retirees should review plans with a fiduciary now.