Legal Question in Civil Litigation in California

If you both claim the same kids as dependents, the IRS will likely audit both of you and will disallow at least one claim. It sounds like your girlfriend's mom will be the one who deserves to get into trouble, but that doesn't necessarily mean the IRS will see it that way. I suggest consulting a tax lawyer before you file your returns. Your girlfriend's mother may want to do the same thing.

You cannot claim them on your taxes unless they are your children, since you are not married to your girlfriend and it does not sound like you are their legal guardian. You can't claim her either, since you are not married and you are not her guardian. You don't get a dependent credit unless there is some legal obligation of support or blood relation. You can't just take a non-relative and deduct them because you pay their bills. It sounds like your girlfriend will not be paying any taxes, or even filing a return. So she cannot claim herself or her kids. So what's your problem with the mom taking the dependent credit? Why lose the deduction and let the IRS take more then they should get?