If you have been living apart for over 6 months, you can file as single. Also, if you do file married filing seperately, if one itemizes they other has to also.
I only say this because my coworker was audited last year. She has been living away from her husband( didn't file for divorce though) for over a year. She filed Head of Household. She mailed in her rental agreement, her sons school records, and her husbands address(he file as single). The IRS agreed that she could file head of household.
This post was edited on 1/10 at 3:49 pm