The taxable portion of your Social Security benefit counts towards IRMAA; the non-taxable portion does not. Under IRS rules, up to 85% of a Social Security benefit can be taxable depending on your other income, and whatever amount is taxable flows into the adjusted gross income Medicare uses when setting IRMAA — the income-related surcharge on Part B and Part D premiums.
Revised: 7/24/26
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The long answer
The full measure is modified adjusted gross income — adjusted gross income plus tax-exempt interest — taken from your tax return of two years earlier. Since IRMAA does not begin until that figure passes $109,000 for a single filer or $218,000 for a joint filer, per the Social Security Administration, Social Security benefits alone essentially never trigger it.
What benefits do is stack. IRA withdrawals, pensions, dividends, and capital gains fill the bucket first, and the taxable share of Social Security rides on top. In a year already close to a threshold, that share can be the piece that tips the total across.
One related mechanical note: the relationship runs the other way, too. If you receive Social Security, your Part B premium — including any IRMAA — is normally deducted straight from the monthly benefit, so a surcharge shows up as a smaller deposit rather than a separate bill.
Printed from JasonKnowsMedicare.com — “Does Social Security Count Towards IRMAA?”. The free IRMAA Planning Guide is available at tally.so/r/81gEEA · Questions: (850) 810-1000
This page is educational information, not personal financial, tax, or legal advice. For decisions about your own situation, talk with a qualified professional.