You do not mention who your dependent is---only certain dependents can be qualifying dependents for head of household filing status.
Am I Head of Household?
What is a "qualifying person" for Head of Household?
If you qualify as Head of Household, when you enter your marital status (single or married filing separately) into MyInfo, and then enter your qualifying dependent, TurboTax will offer HOH as your filing status.
Head of Household filers can have a lower taxable income than single filers. They also can have greater potential refunds.
To qualify, you have to meet certain criteria. To file as Head of Household, you have to: