tax form

[1956]

 can  tax payers claim his girlfriend on his tax return.

[IRonMaN]

Maybe.  Maybe not.  You are awfully light on details.

[George4Tacks]

Exemptions https://apps.irs.gov/app/vita/content/globalmedia/dependency_exemptions_4012.pdf

Support https://apps.irs.gov/app/vita/content/globalmedia/teacher/worksheet_for_determining_support_4012.pdf

So a definite MAYBE

[qbteachmt]

If his girlfriend is a Minor, maybe.

If he is a Minor, maybe.

Which tax preparation program are you using for this client's return?