These ONESOURCE APIs use a REST architecture that provides communication via the Thomson Reuters API gateway and allows you to directly access the Thomson Reuters Calendar content library resources to calculate the due states for specific obligations. Thomson Reuters ONESOURCE™ Calendar automates the process of monitoring and tracking tax-related activities and due dates, enabling clients with the ability to automate tax obligation and calculation due dates on tax returns. The Calendar service is built with two parts to; identify the actual tax obligations and calculate the due dates for specified periods of time. The provider actively searches, maintains, and updates a content library for tax requirement dates and other statutory obligations and is a global provider of answers that help professionals make decisions about businesses. This includes help with legal, tax, compliance and more. Thomson Reuters is a global provider of news and information based tools.