So, if filing jointly would cause both my wife and me to be affected by IRMMA, couldn't we file separately and list the entire amount of income on mine and nothing on hers???

Hi. I assume that you could choose to file your taxes listing your status as 'married filing separately', but since I'm not a tax expert I can't tell you any specifics. Furthermore, following your plan could end up causing you to pay even higher premiums depending on your and your wife's total incomes. You should probably review the IRMAA charts on the following Medicare webpage before making a decision: https://www.cms.gov/newsroom/fact-sheets/2022-medicare-parts-b-premiums-....

Best, Jerry