I'm trying to figure out my 2023 self-select pin, where can I find it?? I don't need it in the sense to file my taxes, but apparently my ex-spouse needs it to file theirs

[cvichienrat]

I'm being asked by my ex-spouse for my self-select pin I used on last years (2023) tax return. I can't find it albeit being told that it's supposed to be on my 1040.