should the court grant the non-custodial parent the right to claim the dependent. in order for them to properly file his/her federal taxes and claim the dependent they are supposed to obtain form the custodial parent a signed form 8332. that has to be included with their 1040 which thus would require mailing. the alternative is to use form 8453 so the 1040 can be e-filed and then the 8453 and 8332 are mailed according to the 8453 instructions.
