My wife and I are retired, I receive a pension ($55K) and I am not enrolled in Medicare part "B". My wife also receives a pension ($49K) and IS enrolled in Medicare part "B".
I know Medicare premiums are based on MAGI. Combined the MAGI is about $81K but individually that’s not the case. If filing separately, would my wife’s Medicare premiums for part “B” be the minimum of $170.10?

Also, I moved over $125K from an IRA to a ROTH IRA which were both in my name and not my wife’s name. And of course that drastically increases our MAGI to over $200K. So the same question: If filing separately, would my wife’s Medicare premiums for part “B” be the minimum of $170.10?

Hi. If your wife files her income taxes separately and if her MAGI (Modified Adjusted Gross Income) is less than roughly $91,000, then she'd only have to pay the standard Part B premium rate. However, when determining a person's Part B premium rate for a given year, Social Security typically uses the MAGI from their tax return for 2 years prior to that year.

Therefore, your wife's 2022 Part B premium rate will likely be based on her MAGI from her tax return for the year 2020. If you and your wife file separate returns for 2021, her MAGI from the 2021 return will be used to determine her Part B premium amount for 2023.

Best, Jerry