rjs
Level 15
Level 15

Retirement tax questions

MAGI is calculated differently for different purposes. There are about a dozen different definitions of MAGI, depending on what it is being used for. MAGI for the increased premiums for Medicare Parts B and D is different from MAGI for the Roth IRA contribution limit. So there can't be one calculator for all the different ways of calculating MAGI.


MAGI for increased Medicare premiums ("IRMAA") is simply AGI plus tax-exempt interest. But your IRMAA is based on your MAGI from two or three years ago. For example, your IRMAA for 2023 will usually be based on your 2021 tax return, or possibly your 2020 tax return. On your 2020 or 2021 tax return, the MAGI for IRMAA is Form 1040 line 11 plus line 2a.


Calculating MAGI for Roth IRA contributions is more complicated. You have to use Worksheet 2-1 on page 39 of IRS Publication 590-A. If you receive Social Security benefits, be sure to read the Note at the bottom of Worksheet 2-1 and follow the instructions there.