I cant remember my seperated wife SSN or her birthday. What to fill in this info?

[scary2222]

I cant fill in my seperated spouse info, what do I do?

[NCperson]

use 111-00-1111 for her social security number.  Just estimate her birthdate - it's not going to matter. 

you will need to paper file the return; e-file is not available in this circumstance. 

[bosso3]

You may be able to find the info on previous tax returns you filed jointly.

You also have the option of contacting her, or her attorney, since how she filed may affect how you must file:  eg: if she itemized you must itemize.  If she did not itemize you must not itemize.

[Critter-3]

Under no circumstance should you try to file a joint return without her permission ... so if she will agree to file jointly then she can provide the missing information.