If the divorce was final by 12/31, you can file as single on your tax return.
If the divorce was not final by the end of the year and you need to file as married filing separate, you can do the following if you cannot obtain your former spouses information:
- Call the IRS at 800-908-9946, or use the IRS Order a Transcript tool to request a tax return transcript for the last year you filed a joint tax return. The transcript would have her social security number on it.
- File Form 4506-T, Request for Transcript of Tax Return to request the tax return transcript.
- In the worst case scenario, file your return by mail without her social security number and include a letter explaining that she refused to provide that information.