Under the Terms of Use, Sellers whose bid prices exceed their contract ceiling price when the Unison Marketplace fee is added must provide documentation of their ceiling prices so that proper fee adjustment can occur. Unison Marketplace requires documented proof of a GSA Schedule (or other contract) ceiling price prior to fee adjustment in order to ensure that fees are adjusted correctly and so that there is a documented paper trail explaining any changes that are made. Providing documentation in a timely manner (i.e. at the close of the Buy) not only ensures that Unison Marketplace correctly assesses the fee it has earned on a given Buy, it also helps the Buyer by preventing unnecessary purchase order modifications.