"Mother previously revoked all future years from Father with form 8332 but the court never modified the original order to allow this."
Q. Would the IRS accept her revocation over the original decree?
It's not really relevant, since the child now lives with the father. But, since this is a a pre 2009 decree, the non custodial father doesn't usually need form 8332. He attaches copies of the relevant pages to his tax return. If the court didn't revoke it, it's still valid (caveat: I'm not a lawyer)
Another issue: How old is the child? Is he/she emancipated. An emancipated child is in neither parent's "custody" and the special rule for divorced/separated parents not longer applies (the tax benefits cannot be "split"). But who the emancipated child lives with is still important for tax purposes.
A child of a taxpayer (emancipated or not) can still be a “Qualifying Child” (QC) dependent, regardless of his/her income, if:
- He is under age 19, or under 24 if a full time student for at least 5 months of the year, or is totally & permanently disabled
- He did not provide more than 1/2 his own support. Scholarships are considered third party support and not as support provided by the student.
- He lived with the parent (including temporary absences such as away at school) for more than half the year
