If I send a cashier's check with my name and Social Security number but without paperwork to the IRS center for my state, will they cash it?

if my grandmother grows a beard, can i call her grandpa? It's one of those unanswered age-old questions.

Yes

The BANK that receives mail sent to the address listed for tax returns including payments will return it to the bank it is drawn against.

Update in response to your comment: I used to work in the bank mail room and personally received the checks. I also knew people that worked in the department that receives mail addressed to the PO Box for tax returns with payments enclosed. The IRS would NEVER know the check existed.

Did you lose the paperwork? My guess is "yes".

They don't cash checks...they deposit them and they don't have any issues depositing any payment methods received...

Yes they will and they will post it to your social security number, but they won't necessarily know what tax or time period to apply it to.

They will cash it, but they might not know which tax bill to apply it to. You could end up still owing tax for 2018 and having a credit for 2019.

without a thought ....................................

If you sent it to me, I would