I am filing separately from my wife I don't know her social security number?

[DavidD66]

If you are married and file separate and don't have your spouse's social security number you will have to print your return and file by mail.  You won't be able to e-file.  You should Include a letter explaining why you don't have your spouse's social security number is missing.  When printing your return, ignore any SSN error messages.

If you are filing separate, you spouse will also have to file separate, and will need your social security number.  Perhaps the two of you can agree to exchange SS Numbers.