Thanks very much for the detailed response. The only part I could see as possibly having some relevance with respect to 2023 taxes is this bullet.
• State and local estimated tax payments made during 2023, including any part of a prior year refund that you chose to have credited to your 2023 state or local income taxes.
When I filed my 2022 taxes (in 2023) I received a 1626 refund which I did not have credited to my 2023 taxes. So does that mean that line IT201 line 76 for 2023 would have been adjusted down by that amount when calculating IT196 line 5? (That still would not fully explain the IT196 line 5 as it would have made it 6241, not 6485.)
