Some Medicare beneficiaries can face high premiums as a percent of income for Part B and Part D, even with support programs. In this brief, we estimate the effects and costs of two national policies that would limit the financial burdens of premiums for Part B and Part D faced by Medicare enrollees with low incomes. We find that a cap on premiums at 8.5 percent of income would provide some financial assistance to nearly all enrollees with incomes below the federal poverty level (FPL) and many with incomes between 100 and 200 percent of FPL without substantially raisingMedicare program spending. Applying the more generous income caps that the Inflation Reduction Act setsfor nonelderly populations underthe ACA would provide financial assistance to all Medicare enrollees with incomes below 200 percent of FPL and nearly half of enrollees with incomes between 200 and 400 percent ofFPL, butwould raise total Medicare Part B and Part D program spending by about 8 percent.