No...it doesn't
To get that particular MAGI value, you usually just add your line 11 to line 2a of your 2024 form 1040...and that is your MAGI for IRMAA purposes.
(that's the sum of your AGI, added to your Tax-Exempt Interest).
The SSA gets that data from the tax return you file with the IRS. (Not sure how much other data they share)
Thanks for your help. Your answer looks correct except for some reason there is always a small non-taxable amount on my 1099R (5a vs 5b) that I'll add so I definately don't underestimate MAGI.
MAGI for IRMAA is simply Adjusted Gross Income (AGI) plus tax-exempt interest. But your IRMAA is based on your MAGI from two or three years ago. For example, your IRMAA for 2024 will usually be based on your 2022 tax return, or possibly your 2021 tax return. On your 2021, 2022, or 2023 tax return, the MAGI for IRMAA is Form 1040 line 11 plus line 2a. See
SSA - POMS: HI 01101.010 - Modified Adjusted Gross Income (MAGI) - 01/05/2024
Yes they look back a couple years to figure the IRMAA for the next year.