I live with my girlfriend and we file separate. we both pay 1/2 of everything. she claims 3 kids, i claim 1. can we both file head of household? if not, what do we do?

[rjs]

Only one person in a household can file as head of household. One of the requirements for head of household filing status is that you paid more than half of the cost of keeping up a home for the year. Only one of you can pay more than half of the cost of keeping up the home. If one paid more than half, the other must have paid less than half.

If you really split all the household expenses exactly equally, then neither of you can file as head of household, since neither of you paid more than half of the cost of keeping up the home.

[DawnC]

No, one of you has to file Single and one of you can be Head of Household.   There can only be one Head of Household per household, so you both can't qualify.   When you get the question that asks ''Do you provide more than half the costs of keeping up a home?'' - only one of you can answer yes to that.   If you both pay exactly half, then neither of you qualify for head of household.   The person who pays MORE than half (even if it is only $1 more) gets to claim the Head of Household status.    If you both claim the HoH status at the same address, expect an IRS inquiry as that can only be done in limited circumstances, as in when you are running two completely separate households.  A boyfriend and girlfriend living together would not be one of the acceptable situations.  

''Married filing separately'' is an option only for married taxpayers so you don't have the option.  And you would not want it anyway as it is usually the worst filing status for a taxpayer.  😉  

[rjs]

If one of you files as head of household, the other has to file as single.