Medicare and IRMAA
Can a Roth Conversion Affect Medicare IRMAA?
Conversion income can raise modified adjusted gross income used for Medicare IRMAA, often with a two-year lookback, so timing deserves explicit review.
Written by Agent Roth Editorial Team
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The short answer
Direct answer
Yes. The taxable portion of a Roth conversion generally increases adjusted gross income and may raise the modified adjusted gross income used to determine Medicare income-related monthly adjustment amounts for Part B and Part D.
Social Security generally uses tax-return information from two years before the premium year. Thresholds and premium amounts change, so the relevant year’s official tables—not an old article—should be used when modeling a conversion.
What is IRMAA?
IRMAA is an additional amount paid by certain higher-income Medicare beneficiaries for Part B and Part D coverage. It is separate from federal income tax. The adjustment uses modified adjusted gross income and filing status, with multiple income tiers rather than one flat surcharge.
Because premiums are generally based on earlier tax information, a conversion can affect a later premium year. For example, official guidance for 2026 generally refers to 2024 tax information. The exact lookback and available data can vary in limited situations.
How can a conversion move someone into another tier?
A conversion adds taxable income in a single year. If that addition moves modified adjusted gross income above an IRMAA threshold, the household may pay higher Part B and Part D amounts in the corresponding premium year. Crossing a tier can affect premiums even when the conversion dollars themselves are no longer in a pre-tax account.
This does not mean every conversion near Medicare is unfavorable. The review should compare the temporary premium effect with the broader tax and account outcomes, and it should test conversion amounts around—but not mechanically target—the applicable thresholds.
What if income later falls?
Social Security has a process for requesting a new IRMAA determination after certain life-changing events, such as work stoppage or reduction. A Roth conversion itself is not automatically a qualifying life-changing event, and the required evidence and eligibility should be confirmed directly with Social Security.
Do not assume that a later retirement will erase an IRMAA effect. Model the premium using the official rule, then separately review whether a new determination may be available for the person’s facts.
What should an IRMAA-aware conversion review include?
Map tax years to Medicare premium years, use the official threshold table for the relevant premium year, and include both spouses when filing jointly. Then compare more than one conversion amount and leave room for uncertain dividends, gains, and other income.
- Medicare enrollment dates for both spouses
- Tax filing status and projected modified adjusted gross income
- The applicable two-year lookback and current official thresholds
- Capital gains, dividends, pensions, and other one-time income
- Potential qualifying life-changing events and documentation
Primary sources
Official sources last verified . Rules and thresholds can change; open the source that applies to the relevant year and account.
- [1]Social Security Administration: Medicare Premiums and Income-Related Adjustments
- [2]CMS: 2026 Medicare Parts A & B Premiums and Deductibles
Related reading
Browse every guideTax Planning Before Retirement
Roth Conversions Before Social Security: What to Consider
Roth Conversion Basics
How Are Roth Conversions Taxed?
Roth Conversion Basics
How Partial Roth Conversions Work
Educational and illustrative only. Not tax, legal, investment, or financial advice. The examples omit facts that may materially affect an actual decision. Review your complete situation and current law with appropriately qualified professionals before acting. Read the educational and financial disclosures.