A Roth conversion and IRMAA — the income-related surcharge on Medicare Part B and Part D premiums — are connected through your tax return: the amount you convert is taxed as ordinary income, raising the modified adjusted gross income (MAGI) that Medicare, two years later, measures against its surcharge thresholds. Convert in 2024 and the income appears in your 2026 premium calculation; convert in any year from about age 63 on, and it can raise what you pay in your first years on Medicare.
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
Many retirees size conversions to fill a tax bracket. The IRMAA tiers are a second set of lines worth drawing on the same map: for a single filer in 2026 they begin above $109,000, $137,000, $171,000, $205,000, and $500,000 of MAGI, per the Social Security Administration, with joint-filer lines at double those amounts except the top. Because each line is a cliff, converting to just under a tier boundary — rather than barely over it — avoids paying a full tier’s surcharge for one extra dollar of conversion.
There is also a longer view that favors converting. Traditional IRA balances eventually produce required withdrawals, and large required withdrawals can push MAGI over the thresholds year after year. Conversions done earlier — sometimes deliberately accepting a surcharge or two — can shrink that future income stream and lower IRMAA for decades.
The two effects pull in opposite directions, which is exactly why this deserves a side-by-side projection rather than a rule of thumb.
Printed from JasonKnowsMedicare.com — “Roth Conversion and IRMAA: What to Know Before You Convert”. 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.