spouse if you file as "married filing separately". Just put an "NON RA" on the SSN line. It was ok for me.
I don't think you can file as "single" if you are married unless, according to the instruction of Form 1040, "You were legally separated, according to your state law, under a decree of divorce or separate maintenance."
I don't think you can file as "single" if you are married unless, according to the instruction of Form 1040, "You were legally separated, according to your state law, under a decree of divorce or separate maintenance."