Retirement calculator
Roth Conversion and IRMAA Calculator
How could a Roth conversion change federal tax and later Medicare premiums?
What this tool helps you answer
How could a Roth conversion change federal tax and later Medicare premiums?
A Roth conversion can fill federal tax brackets now and raise Medicare premiums later. This calculator stacks the conversion on ordinary taxable income using 2026 brackets, adds an entered state rate, and tests modified adjusted gross income against the published 2026 Medicare bands while clearly warning that 2028 values are not yet known.
Transparent method
How the estimate works
See how the estimate is calculated
Calculate 2026 federal ordinary-income tax before and after adding the conversion, then use the difference as the estimated federal conversion tax.
Add the conversion to entered Medicare modified adjusted gross income and find the before-and-after band in the published 2026 Part B and Part D table.
Multiply the monthly premium difference by twelve and the Medicare enrollees entered, labeling it as a planning proxy rather than a future premium quote.
What to check before acting on the result
How to read it
- Compare the conversion tax with the long-term tax reason for moving money to Roth.
- Use the Medicare result as a stress test, not a quote for a future year.
- Run smaller conversion amounts around bracket and IRMAA lines before the tax year closes.
Not included
- Capital gains, qualified dividends, deductions, credits, or additional Medicare tax
- Future 2028 Medicare thresholds or premiums
- Social Security taxation, required distributions, withholding, or estimated-tax penalties
- A recommendation to convert, investment advice, or state-specific retirement exclusions
Common questions
Frequently asked questions
When would a 2026 Roth conversion affect Medicare premiums?
Medicare generally uses tax-return income from two years earlier, so a 2026 conversion would generally be considered for 2028 premiums.
Are 2028 IRMAA thresholds available?
No. The calculator uses the published 2026 table only as a visible planning proxy and does not claim to know future bands.
How is the federal conversion tax estimated?
The conversion is stacked on entered ordinary taxable income and the difference between two 2026 bracket calculations is shown.
Can a life-changing event reduce IRMAA?
Certain qualifying events may support a request to use more recent income, but a voluntary Roth conversion is not itself treated as a qualifying event.
Sources
Rules and references behind this calculator
Want the fine print? See sources, methods, and limits.