A master supply agreement is a legal contract between two parties that consolidates two or more current contracts into one streamlined agreement. This Master Contract defines and provides for coverage and administration for the benefits common to uniform CITY employees.This Amendment and Restatement of the Master Interlocal Agreement Between City of. Prior to bidding on, submitting a proposal or executing a contract or renewal for goods or services of. A master purchase agreement is a legally binding contract between buyer and seller, and typically relates to buying and selling goods rather than services.