Capital gains count fully toward IRMAA, Medicare’s income-based premium surcharge, because taxable gains are part of adjusted gross income — the base of the modified adjusted gross income (MAGI) figure Medicare measures. A large gain from selling stock, a business, or an investment property can push you over a surcharge threshold, with the higher premiums arriving two years after the sale.
Revised: 7/24/26
Jason Baar
Fee-Only Medicare Advisor
NPN #2033715
It covers Roth conversions, capital gains, home sales, filing status, and HSAs — with the 2026 bracket lines and worked examples.
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The long answer
The favorable tax rate on long-term gains does not carry over to Medicare. Whatever rate the gain is taxed at, the full taxable amount enters MAGI. The 2026 surcharge thresholds sit at $109,000 of MAGI for single filers and $218,000 for joint filers, per the Social Security Administration, and crossing the first line adds $95.70 a month across Part B and Part D.
The two-year lag cuts both ways. A 2024 sale sets 2026 premiums — but only 2026. A one-time gain means one year of higher premiums, after which your newer, lower return takes over.
If a sale is on the horizon, the useful questions are about timing and offset: whether the sale can be spread across tax years, whether harvested losses can absorb part of the gain, and where the final-year total sits against the tier lines. Gains realized inside IRAs and 401(k)s, for what it is worth, do not count until money is withdrawn.
Printed from JasonKnowsMedicare.com — “Capital Gains and IRMAA”. The free “Before You Sell the House or Convert That IRA” guide is available at tally.so/r/0QgAAZ · 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.