Roth conversions · Medicare
How does a Roth conversion affect Medicare IRMAA?
By Jim Swiech, CPA · Updated
Quick answer
A Roth conversion raises your modified adjusted gross income for the year, and Medicare uses that figure two years later to set your Part B and Part D premiums. Convert in 2026 and your 2028 premium is decided by it.
In 2026 the first line is $218,000 for a couple and $109,000 for a single filer. One dollar over it raises the standard $202.90 monthly Part B premium to $284.10 per person, about $1,949 more for a couple over the year, before the Part D surcharge.
What IRMAA is
IRMAA is the Income-Related Monthly Adjustment Amount, a surcharge added to Medicare Part B and Part D premiums when your income crosses set lines. It is a cliff, not a slope: one dollar over a line and the full surcharge for that tier applies to every month of the year, for each spouse on Medicare. The income Medicare uses is modified adjusted gross income, which is your adjusted gross income plus tax-exempt interest. A Roth conversion goes straight into that number.
The 2026 lines
| Single | Married filing jointly | Part B monthly | Extra per couple, per year |
|---|---|---|---|
| up to $109,000 | up to $218,000 | $203 | $0 |
| $109,001 to $137,000 | $218,001 to $274,000 | $284 | $1,949 |
| $137,001 to $171,000 | $274,001 to $342,000 | $406 | $4,870 |
| $171,001 to $205,000 | $342,001 to $410,000 | $528 | $7,790 |
| $205,001 to $499,999 | $410,001 to $749,999 | $649 | $10,711 |
| $500,000 and up | $750,000 and up | $690 | $11,688 |
Part D has its own surcharge on the same lines, from roughly $14.50 to $91.00 a month per person in 2026, on top of the Part B figures above.
The two-year lookback
Social Security sets each year's premium from the most recent tax return the IRS has on file, which is normally the return from two years earlier. The 2026 premium came from the 2024 return. A conversion you do in 2026 shows up on the return you file in early 2027 and sets the premium you pay in 2028. People are often surprised twice: once when the premium letter arrives 14 months after the conversion, and again when it applies to both spouses.
Can the surcharge be appealed?
Only for a life-changing event. Form SSA-44 lets you ask Social Security to use a more recent year's income after retirement, a reduction in work hours, marriage, divorce, the death of a spouse, or the loss of income-producing property or a pension. A Roth conversion is not a qualifying event, and neither is a large capital gain. The surcharge caused by a conversion stands for the year. The protection is on the front end, which is what the calculator on the Roth conversion page is for.
When crossing the line is still worth it
Sometimes. If a large conversion this year keeps you under the line for the next ten years by shrinking future RMDs, one year of surcharge can be the cheaper path. That is a calculation across years, not a rule. What never makes sense is crossing a line by accident, by a small amount, for one conversion that could have been split across two years.
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Quick answers
- How does a Roth conversion affect Medicare IRMAA?
- A conversion raises your modified adjusted gross income for the year, and Medicare uses that figure two years later to set your Part B and Part D premiums. Convert in 2026 and your 2028 premium is decided by it. If the conversion pushes you over an income line, both spouses on Medicare pay the surcharge for the full year.
- What are the 2026 IRMAA income lines?
- For a married couple filing jointly: $218,000, $274,000, $342,000, $410,000 and $750,000 of modified adjusted gross income. For a single filer: $109,000, $137,000, $171,000, $205,000 and $500,000. The standard 2026 Part B premium is $202.90 a month per person. One dollar over the first line raises it to $284.10, which is about $1,949 more for a couple over the year, before the Part D surcharge.
- Can you undo the IRMAA surcharge caused by a Roth conversion?
- Not because of the conversion itself. Form SSA-44 lets you appeal a surcharge after a life-changing event such as retirement, reduced work hours, marriage, divorce or the death of a spouse. A conversion is not one of those events. The protection is on the front end: know where the line is and convert up to it, not over it.
Updated . Reviewed by Jim Swiech, CPA.
Educational and general in nature. Not tax, legal or investment advice, and not a recommendation to convert. Figures are 2026 federal amounts under the assumptions stated on this page; your return has more lines than any example. Go Beyond Tax is a brand of Swiech Consulting LLC.