there are many other rules besides having dependents please read the following
1) was the dependent claimable solely because of a multiple support agreement - if yes you cannot file as HOH, if no was the dependent legally related to the taxpayer by blood - if no you cannot file as HOH.
2) Do you qualify as a surviving spouse because your spouse died in the preceding 2 years and you maintain a home for a child whom you are able to claim as a dependent whether you do or not - you cannot file as HOH but as surviving spouse.
3) Were you a nonresident alien at any time during the year - if yes you cannot file as HOH.
4. was the dependent a married child of the taxpayer? if yes, will the dependent child file a joint return with their spouse? if yes you cannot file as HOH. If the dependent child was not married or if married will not file a joint return with their spouse then did the legally related dependent use the taxpayer’s household, for which the taxpayer paid at least ½ the cost, as their principal place of abode for more than ½ the year – then you can file as HOH.
Am I 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.