head of household for unmarried couple with biological child and child from a previous relationship

I am unmarried with a biological child living with me and my girlfriend. I pay more than 1/2 of the expenses pertaining to the biological child. My girlfriend also has a son from a previous relationship that lives with us. Can we both claim head of household with me claiming my daughter and her claiming her son?

posted

Since you both live in the same household, No you cannot both claim head of household. One of you must be providing over one-half the cost to maintain the home, even if only by $1. That person can have Head of Household and other person can only file as Single.