Head of Household

[joemalone1967]

Taxpayer is single and lives with his girl friend and her children.  He has not adopted the children nor is he a foster parent. The father of the children does not provide any financial support.  The taxpayer's  income is greater than his girlfriend's.  Can he claim the children as dependents??  Can he file as head of household??

[VolvoGirl]

Don't know if he can claim them but they won't qualify him for Head of Household.  Has to be a related dependent.  

Who is a qualifying person for Head of Household?
https://ttlc.intuit.com/community/family/help/what-is-a-qualifying-person-for-head-of-household/00/2...

[Hal_Al]

Q. Can he claim the children as dependents?

A.  No.

There are two types of dependents, "Qualifying Children"(QC) and standard ("Qualifying Relative" in IRS parlance even though they don't have to actually be related). There is no income limit for a QC but there is an age limit and student status test, a relationship test and a residence test. 

The children cannot be your QC (or qualify you for Head of Household) because they are not related. A person can still be a Qualifying relative dependent, if not a Qualifying Child, if he meets the 6 tests for claiming a dependent:

1. Closely Related OR live with the taxpayer ALL year
2. His/her gross taxable income for the year must be less than $4300 (2020).
3. The taxpayer must have provided more than 1/2 his support
4. He must be a US citizen or resident of the US, Canada or Mexico
5. He must not file a joint return with his spouse or be claiming a dependent of his own
6. He must not be the qualifying child of another taxpayer

In addition to the above requirements, to claim your girlfriend's children, they must meet all of the above requirements and:
--- your girlfriend must not be required to file a return,
--- he/she does not file a return claiming the children

So, basically because your GF has enough income to have to file, you cannot claim her children.  You probably don't meet the support test either.