FYI. the IRS only cares about physical custody - that parent gets the dependent unless that parent provides form 8332 to the noncustodial parent. the courts care about the legal agreement. whether an oral modification has any legal effect (it should be anticipated that your ex will deny the oral modification) would take a lawyer to answer. consult one before you do anything because you could find yourself taken to court by your ex and found in contempt.
