I am a working adult. I care for a non working adult who received SSI. She pays me rent and I pay for utilities, as her income cannot support this payment. She pays for 60% of her food, and I payh for 40%. This year(2018) I want to know can I legally claim her as a dependent and file as head of household.
Is the adult you "care for" related to you? If not, she cannot be a qualified dependent for you to use for filing as Head of Household. You might be able to claim her as a dependent and get the $500 credit for other dependents for her.
Am I Head of Household?
If you qualify as Head of Household, when you enter your filing status (single or married filing separately) into Personal Info, and then enter your qualifying dependent, TurboTax will offer HOH as your filing status.
CREDIT FOR OTHER DEPENDENTS
Then you can claim your daughter as a qualifying dependent and file as Head of Household. Read through the criteria already posted in the links that were given to you.