Can I file as head of household if I'm separated but not yet divorced?

Possibly, under the IRS 'considered unmarried' rule. If you are still legally married but lived apart from your spouse for the last six months of the year, paid more than half the cost of keeping up your home, and had a qualifying child living with you for more than half the year, you may file as head of household even though you are not divorced. This gives you a larger standard deduction and more favorable brackets than married filing separately. The rules are strict, so confirm each condition carefully. If you do not meet all of them, your options are married filing jointly (if your spouse agrees) or married filing separately. The IRS interactive filing-status tool can confirm eligibility.