Proof of Claim

A written statement describing the reason a debtor owes a creditor money, which typically sets forth the amount of money owed. (There is an official form for this purpose.)

Additional Sources

Answers.com

A document filed with a court by a creditor to verify position as a holder of debt.

Lawyers.com

A written statement that sets forth a claim against a bankrupt debtor or the probate estate of a deceased debtor.