Okay, I solved my own problem. Sharing here in case someone else has the same issue.
This does appear to be a bug in TurboTax, but not the way that I thought. What is happening is that MN has a standard deduction limitation, which means that if your income is over a certain threshold the standard deduction is reduced. TurboTax was doing this calculation for me, and because of that reduction it turns out that my itemized deduction total is slightly higher than the limited standard deduction (by just a few dollars). This means that I am filing Schedule M1SA and thus I can't / don't need to add charitable contributions on Schedule M1M. I confirmed that if I remove some of the charitable contributions, so that itemized total is below the limited standard deduction, that it flows the charitable contributions into Schedule M1M as expected.
So there are two things that led to my confusion.
- The fact that the number for charitable contributions when taking the standard deduction just disappears instead of providing an explanation for why it can't be entered — that's a bad design choice.
- There is a bug where the TurboTax tells me that I'm taking the standard deduction, even though it's calculated that the itemized deduction would be preferable and the actual forms show that I'm taking the itemized deduction. It appears to me that TurboTax is smart enough calculate the MN standard deduction limitation amount behind the scenes, but not smart enough to use that figure on the screen where it tells me whether I'm taking the standard or itemized deduction.
