It is possible to do so, but it is up to the IRS to determine if both people are running separate households or are in a family relationship.
Taxpayers who share the same physical address will need to prove whether they "conduct themselves as separate households or one household" and especially "whether each family acts independently of each other in matters not related to the house."
Some factors that would weigh in favor of there being two separate households but sharing the same residence might include:
Are there separate telephone lines for each family? Separate utility bills?
Do the taxpayers maintain separate finances and separate bank accounts? Or do they have a joint account or commingle funds?
Does one family contribute to the financial support to the other?
Do the adult taxpayers have separate bedrooms?
Do the children have separate bedrooms?
Do the family members give Christmas and birthday presents together or separately?
The IRS will attempt to figure out whether the taxpayers act as a family unit, or whether the taxpayers act as separate from each other. The more that two taxpayers act like they are in a family relationship, the less likely the IRS will allow both taxpayers to claim head of household.
Bot***** *****ne - There can only be one HOH per household since this requirement is that you paid 51% of the total household expenses. But there could potentially be more than one household per home. If there is more than one household and each taxpayer paid more than 50% of their respective households, it is possible to have more than one taxpayer meet the HOH filing status even if they live at the same place.