What Is IRMAA?
IRMAA stands for Income-Related Monthly Adjustment Amount. It is a surcharge added to your Medicare Part B and Part D premiums when your income goes above certain thresholds.
The Two-Year Lookback
Your 2026 Medicare premiums are based on your 2024 income. That is the two-year lookback. What you earned in 2024 sets what you pay in 2026.
What Counts as Income?
Social Security uses MAGI, or Modified Adjusted Gross Income. That is your AGI plus tax-exempt interest.
2026 IRMAA Brackets (Based on 2024 MAGI)
Figures per CMS, November 2025. The standard Part B premium is $202.90 per month.
- Single $109,000 or less / Joint $218,000 or less: No surcharge. Part B stays at the standard $202.90 per month.
- Single $109,001 to $137,000 / Joint $218,001 to $274,000: Part B $284.10 per month + Part D $14.50 per month.
- Single $137,001 to $171,000 / Joint $274,001 to $342,000: Part B $405.80 per month + Part D $37.50 per month.
- Single $171,001 to $205,000 / Joint $342,001 to $410,000: Part B $527.50 per month + Part D $60.40 per month.
- Single $205,001 to $499,999 / Joint $410,001 to $749,999: Part B $649.20 per month + Part D $83.30 per month.
- Single $500,000 or more / Joint $750,000 or more: Part B $689.90 per month + Part D $91.00 per month.
Watch Out for the Cliffs
These are cliff tiers, not gradual steps. Go one dollar over a threshold and you move into the next tier. The higher surcharge applies to your premium. A single dollar of extra income can cost you hundreds per month.
Why This Matters in South Carolina
This is especially relevant for retirees managing RMDs, planning Roth conversions, or realizing capital gains. A large Roth conversion or a big capital gain in one year can push you into a higher IRMAA tier, raising your Medicare costs two years later. Timing matters.
Can You Appeal?
Yes. If you have had a life-changing event such as retirement, divorce, or the death of a spouse, you can file Form SSA-44. This asks Social Security to base your premium on your current income instead of the older figure.
The Bottom Line
IRMAA is not random. It is math based on your tax return from two years ago. Knowing the brackets ahead of time helps you plan around RMDs, Roth conversions, and capital gains.
Want help understanding what IRMAA means for your situation? Call for a no-cost consult: (803) 415-7794.