filing joint tax while divorcing

Yes. Your marital status is determined as of the close of December 31 of any given year. If you are married at that time, you and your spouse (even if estranged) can file a joint tax return. While you could file "married filing separately" you cannot file as "single" if still legally married. If however, your divorce is final on December 30, you are considered single for that entire tax year and cannot file a joint tax return for the year.