@rob-gunning wrote:
She is under 24 and a full time student who pays for less than half of her support, so I think she qualifies there.
Also, her mother is remarried and can't file as Head of Household, so can't claim her as a qualifying child. So still ambiguous to me under the tiebreaker rules in the document that you linked.
There are two possibilities, but neither one helps you.
The custody agreement no longer controls who can claim your daughter, if she is emancipated (18 in most states, 19 or 21 in a few). Therefore, either:
1. no one can claim her as a dependent unless she physically lives in their home more than half the nights of the year.
2. or, the parent who can claim her as a dependent is the parent she would have physically lived with more than half the nights of the year but for the fact she was away at college.
Since you indicated she generally spends about 35% of her time with you (or "spent", before going to college), you would not be the parent where she lives "more than half the nights of the year including temporary absences" and you could not claim her as a dependent or a qualifying person for HOH. Even though she is not a qualifying person for your ex-spouse, she may be a dependent of your ex-spouse.
The key point is that any custody agreement allowing you to alternate years with your ex dissolves with respect to an emancipated child and you have to fall back on the normal rules for dependents.
If you think different, you should get professional advice, or file and take the audit risk.
