Know which income year matters
Medicare generally uses tax information from two years earlier to determine income related premium adjustments. A large capital gain, Roth conversion, or retirement distribution may affect premiums later, even when the transaction made sense for the broader plan.
Coordinate the income calendar
Retirement dates, Social Security, pension elections, charitable giving, and portfolio withdrawals can change taxable income from year to year. Mapping those events together can reveal years with more or less planning flexibility.
Keep the decision in perspective
Avoiding a premium increase is not automatically the best outcome. Compare the added Medicare cost with the long term tax, investment, and cash flow benefits of the decision under consideration.