In business dealings, transactions often occur that include variables based on future events that can be difficult to ascertain (for example, a company may sell in an amount stock along with a percentage of that company's net profits.) As these transactions are contingent on payments that occur in the future, and the total selling price cannot be determined as of the end of the taxable year of the sale, they are known as Contingent Payment Sales. Because of the uncertainty surrounding the final amounts of these transactions, they are difficult to evaluate for the purpose of tax liability. Section 483 of the Internal Revenue Code provides descriptions for the handling of contingent payments and interest on contingent payments.