@Mfurstoss - there are a number of triggers to be able to file HOH when you are legally married - you must pass ALL these tests.
1) you are legally married on Dec 31.
2) You must be legally separated or lived apart for the last 6 months of the year. if he moves out on the morning of Dec 31 and a legal separation agreement was signed later that day, then you meet the requirment. Without that legal separation agreement, then the '6 month rule' applies.
3) You must file separate returns
4) You must have paid more than 1/2 the cost of keeping up your household. If he moved out on Dec 31 and was paying more than 50% of the cost of keeping up the househould, you would fail this test
5) your home is the main home for your child for than 1/2 the year. In other words, your child lived with you for at least 1/2 the year. (I assume this involves a child, if a parent, there are rules for that as well)
6) you claimed the child as a dependent (unless the other parent claims the child under rules for children of separated parents)
best to run through the offical IRS tool:
https://www.irs.gov/help/ita/what-is-my-filing-status
does that help?
