what if i don't know the ssn of an ex spouse that alimony is paid to?

[heidie-oh]

how do i find the ex-spouse's social security number to claim alimony that was paid?

[xmasbaby0]

When was the divorce finalized?

From the IRS

Deducting alimony paid. Alimony is deductible by the

payer, and the recipient must include it in income if you

entered into a divorce or separation agreement on or be-

fore December 31, 2018. Alimony paid is not deductible if

you entered into a divorce or separation agreement on or

before December 31, 2018, and the agreement is

changed after December 31, 2018, to expressly provide

that alimony received is not included in your former spou-

se’s income. Alimony paid is not deductible if you entered

into a divorce or separation agreement after December

31, 2018.

If your divorce occurred prior to 2018----what have you been using for the past few years when you needed to enter a SSN?

[KrisD15]

To clarify, when was your divorce final?

You may not need to report it. 

According to the IRS:

"Generally, alimony or separate maintenance payments are deductible by the payer spouse and includible in the recipient spouse's income if paid under a divorce or separation agreement executed before 2019.

You can't deduct alimony or separate maintenance payments made under a divorce or separation agreement (1) executed after 2018, or (2) executed before 2019 but later modified if the modification expressly states the repeal of the deduction for alimony payments applies to the modification. Alimony and separate maintenance payments you receive under such an agreement are not included in your gross income."

@heidie-oh