I have a client who divorced husband. She is custodial parent and files return as head of household. She is now getting back together with ex-husband and buying a house with him and they will be living together. Is she able to still file head of household once she moves in with ex-husband in the new house that is titled in both of their names? He is the higher wage earner. I am thinking if she pays over half the cost of keeping up the home for the daughter then she could. But how do you prove the ex-husband is not helping her with house costs? Would she need to pay over half the house expenses/food out of her separate bank account to prove that she paid for more than half the expenses? However, that just doesn't seem right. Any help would be appreciated!