Oh, thank you - I just looked at my own 8606s and 5498 and the $8000.05 (the 5 cents didn't even get entered) I converted in 2025 was from the $8000 I deposited in January for *2024* contribution, so I bet he did the same thing because he got a 1099-R for $8004.37 and I got one for $8000.05 for 2025 conversions. So actually, we haven't made 2025 contributions yet! I'll have to ask him for his 5498 to confirm that his contribution in early 2025 was actually made for 2024 and that he didn't make another.
My 8606 for 2024 filed in 2025 shows the $8000 contribution made early in 2025 (I just looked and it was January 30) for 2024, converted a few days later for $8000.05 and I had no prior basis, but I did have $1000 left in my IRA on 12/31/2024 so line 10 was 0 and all my conversions were taxable in 2024 so line 14 basis became the $8000 I'd contributed in January. Therefore this year line 2 is $8000 but he and I both have to contribute $8000 more for 2025 before we file. Once I do that, my basis will be $16000 and his will be $16001 his $8004 will not be taxed and I'll be able to subtract $16000 from my 2025 conversions.
