There does not seem to be a clear answer to this question. In most cases, the custodian only requires a certified copy of the Divorce Decree, which clearly identifies the IRA to be divided (i.e. name of the custodian and the account number), the award and the identity of the parties. In many cases, this, along with transfer forms provided by the custodian is sufficient to divide the IRA. In some cases, the custodian may request a letter of instruction, which is a letter that describes the assignment in more detail and is signed by both parties. However, in some cases, the custodian may request a QDRO. I would suggest a call to the account representative or custodian to determine what is required.
Richard Johnston Jr. is a Pension & Profit Sharing Plan Specialist at QDRO Services, L.L.C. that will work with you and your family law practitioner with the division of retirement benefits and a QDRO solution. He can be reached at 1-877-531-8333.