@FedUpParent
If your daughter files a tax return, she has the absolute first right to claim her children as dependents and she can’t be claimed as a dependent by you in that situation.
If your daughter does not file a tax return, or if she files a tax return but does not claim her children as dependents, then you can claim your grandchildren as dependents as long as your taxable income is higher than the taxable income of their mother (your daughter). This is based on the fact that they lived with you more than half the night of the year.
As long as your daughter is age 23 on December 31, and is attending college full-time as defined by the college, then you can claim her as a dependent as well, she would have to check the box on her tax return that says “I can be claimed as a dependent by someone else” and she can’t claim any dependents.
However, be aware that even though the rules would allow you to claim both your daughter and grandchildren as dependents, if your daughter does file a tax return and claims her children as dependents, it will be very hard to get the IRS to overturn that, and it will involve a fight between you and your daughter over providing adequate documentation of your living situation to the IRS.
The boyfriend or ex-spouse or other parent, whatever he is, has absolutely no legal standing to claim the children as dependents on his tax return unless the two of them get married before December 31. And they can’t legally file a joint return unless they get married. But again, if you wanted to force the issue and claim the children as dependents but they also file and claim the children, your claim will force an IRS investigation that could go very negative for your daughter and her family. You should be aware of the ramifications of your choices.
