I don't talk to my ex wife and I doubt she will give me her social security number. What can I do

[MaryK4]

Why do you need your ex-wife's number?

@decembernite2424

[NCperson]

if she is your ex wife (as of 12-31-19),  then why would you need it?

if the divorce was final in 2020 and therefore you are filing married-separate, just print out the return and mail it in.  You can't efile.  just put a dummy SS# in the field if it's a required field.  IRS will figure it out.