Any payment made to a creditor for a pre-existing debt in the 90 day period before a debtor files bankruptcy (or within one year if the creditor was an insider) that gives the creditor more than it would otherwise receive if the debtor were liquidated in a chapter 7 bankruptcy, is considered preferential. The debtor or a bankruptcy trustee has the right to sue the recipient of a preference payment to recover it for the benefit of the bankruptcy estate, subject to certain defenses. Although this type of transaction usually involves money, it can also pertain to a return of merchandise.