@Imablagg Yes, you can claim your girlfriend's daughter, if she lived with you all year. She is an unrelated person, so she can only be claimed under the "Qualifying Relative (QR) rules.
There are two types of dependents, "Qualifying Children"(QC) and Other ("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. Only a QC qualifies a taxpayer for the Earned Income Credit and the Child Tax Credit. The Other dependent (qualifying relative) credit is worth (up to) $500 per dependent and is non-refundable. That is, it can only be used to reduce an actual tax liability.
A person can still be a Qualifying relative dependent, if not a Qualifying Child, if he/she meets the 6 tests for claiming a dependent:
- Closely Related OR live with the taxpayer ALL year
- His/her gross taxable income for the year must be less than $4300 (2021).
- The taxpayer must have provided more than 1/2 his support
In either case:
- He must be a US citizen or resident of the US, Canada or Mexico
- He must not file a joint return with his spouse or be claiming a dependent of his own
- He must not be the qualifying child of another taxpayer
He must have a US social security number or tax identification number (TIN)
Since she is unrelated, she is not a qualifying person for Head of Household filing status, even though she can be claimed as a dependent.
