Get your taxes done using TurboTax

Modified Adjusted Gross Income (MAGI) is not a single calculated value.  It is defined differently for different purposes.  

For the purpose of Form 8582, the MAGI does not take into account taxable Social Security.  So, the calculation should be accurate in TurboTax.  When you take a look at the Mod AGI Wks for Form 8582, you can see that taxable Social Security is not entered on that form.

For further reference, here is a screenshot from the 2023 Instructions for Form 8582: