If my girlfriend and I have 2 kids can we each claim one? she filed, claimed 1 as dependent and 1 nondependent. I file claiming 1 as a nondependent and got rejected?

[DoninGA]

You do Not claim a nondependent on a tax return.  

She should claim only one of the children as a dependent on her tax return and you would claim the other child as a dependent on your tax return.

[xmasbaby0]

If you are a non-married couple who live together with your child, then only one of you can claim the child(ren) and the one not claiming the child does not enter anything at all on their tax return about the child.   The “sharing” of child-related credits you may have heard about is only possible between divorced or never married parents who live apart and share custody and who have a written agreement to share the credits.    The child’s SSN can only be entered on one tax return.   Any other return with the child’s SSN on it will be rejected.   If you are a family, then work out how to share the refund between yourselves.

If you each decide to claim one child each, only ONE of you can file using Head of Household status---the other one has to file Single.