Can a Roth conversion increase my Medicare premiums?
Yes, it can. The taxable portion of a conversion is included in income for the year it is done, and the measure used for Medicare's income-related adjustment is built on adjusted gross income plus tax-exempt interest. A conversion large enough to move the measured figure into a higher band can raise Part B and drug coverage costs.
The effect is delayed rather than immediate, because the determination generally uses a return from an earlier year. It is also bounded: the adjustment applies to the year determined by that return, and the determination is made again each year.
That makes this a timing question rather than a reason not to convert. This page explains the interaction; it does not advise for or against converting, and it does not calculate an amount or a threshold for you.
IRMAA is measured on an old year and charged in a later one
The adjustment for a given year is normally based on a tax return from an earlier year. That lag is the single most useful thing to understand about it, because it means the cost of an income decision arrives later than the decision.
It also means the premium someone is paying today may describe a year in which they were still working, still selling, or still realising gains.
The tables are bands, not a sliding scale
The published tables set one amount per band. Income that falls into a higher band carries that band's amount rather than a proportionate share of it.
This is why the arithmetic of a planning decision is about where a year's income lands, not only about how large it is.
What a general answer cannot settle
Enrolment requirements, payer order, the band that applies to a household, whether a request to revisit a determination will succeed, and the amount that may still be contributed to a health savings account are all individual determinations made by Social Security, Medicare, the plan or a tax professional on the facts and documents.
This page is written to help someone ask better questions of those parties and to see the connections between decisions. It does not make any of those determinations, and no figure here is calculated for a reader.
Reviewed by Bay Area Wealth Advisors. Last reviewed 2026-09-20. Educational information only — not individualized financial, tax or legal advice.