Retirement calculator
How could a Roth conversion change federal tax and later Medicare premiums?
Estimate 2026 federal tax on a Roth conversion and see which published Medicare income band the added income reaches.
Before you calculate
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.
Before you act on the number
Use the result to identify which assumption needs verification, then bring that question to the professional helping you make the decision.
Transparent method
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.
Common questions
Medicare generally uses tax-return income from two years earlier, so a 2026 conversion would generally be considered for 2028 premiums.
No. The calculator uses the published 2026 table only as a visible planning proxy and does not claim to know future bands.
The conversion is stacked on entered ordinary taxable income and the difference between two 2026 bracket calculations is shown.
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
Want the fine print? See sources, methods, and limits.