deed of assignment
noun [ C ]
ukusplural deeds of assignment (also letter of assignment) LAW
a legal agreement to give an asset or to sell a debt to someone else:
This deed of assignment enables ownership of a life-insurance policy to be transferred from the current owner to another person or organization.
If the debt has been sold by the original creditor, there should be a deed of assignment stating who is now the legal owner of the debt.