You may still qualify for head of household filing status even though you aren't entitled to claim your child as a dependent, if you meet the following requirements:

1. You're not married, or you’re considered unmarried on the last day of the year.
2. You paid more than half of the cost of keeping up a home, that was your home and the main home of your child for more than one-half of the year.
3. Your child is your qualifying child for purposes other than the dependency exemption and the child tax credit.  

See Publication 501, Dependents, Standard Deduction and Filing Information for details.