Form 2120, Multiple Support Declaration
Use this form to identify each other eligible person who paid over 10% of the support of your qualifying relative whom you are claiming as a dependent, and indicate that you have a signed statement from each other eligible person waiving his or her right to claim that person as a dependent.
Form 8332, Release/Revocation of Release of Claim to Exemption for Child by Custodial Parent
If you are the custodial parent, you can use this form to release a claim to exemption for your child so that the noncustodial parent can claim an exemption for the child or revoke a previous release of claim to exemption for your child.
Publication 501, Exemptions, Standard Deduction, and Filing Information
This publication discusses some tax rules that affect every person who may have to file a federal income tax return.