IRMAA Check

IRMAA Cliff

One dollar over an IRMAA threshold can move the whole month into the next surcharge tier for Medicare Part B and Part D.

Check your room before the next bracket
Tax documents, calculator, and laptop arranged for Medicare MAGI planning

Short answer: IRMAA is not a smooth percentage. Medicare uses income ranges. Cross into the next range and the surcharge changes to that tier.

A small income change can trigger the full next surcharge tier
Below threshold $108,999 MAGI
Standard premium
Example for a single filer near the first 2026 threshold.
One dollar over $109,001 MAGI
Standard premium + IRMAA
The full first surcharge tier can apply, not a percentage of the extra dollar.

Why the cliff matters

A small amount of extra Medicare MAGI can create a larger premium change than people expect. This is especially important before year-end Roth conversions, IRA withdrawals, capital gains, or one-time consulting income.

Do not stop just over a bracket

If a plan intentionally crosses a threshold, the better question may be whether the extra income is worth the full surcharge. Sometimes the answer is no. Sometimes the answer is yes because the conversion or withdrawal accomplishes a bigger tax goal. The mistake is crossing the line by accident.

See the 2026 brackets

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Cliff planning checklist

  • Estimate Medicare MAGI before executing a large income event.
  • Find the next bracket, not just the current bracket.
  • Leave a margin for dividends, interest, fund distributions, or tax-exempt interest.
  • Use the calculator again after tax documents are clearer.

Common cliff events

Roth conversions, RMDs, taxable IRA withdrawals, taxable stock sales, home sale gains, and tax-exempt municipal bond interest are common reasons people unexpectedly cross a threshold.

Next step: estimate your surcharge and use the IRMAA planning checklist before the income event.