CASS is an acronym that stands for Coding Accuracy Support System. The system enables the USPS or the United States Postal Service to evaluate the accuracy of the software, that not only corrects but also matches the addresses of streets. If you run a service bureau or if you are a software vendor and would like the USPS to check the quality of your address matching software and improve the accuracy of your five-digit coding, ZIP+4 and carrier route, you can get CASS certification. It is important to note that as a software vendor, you are required to renew your CASS certification every year with USPS. Renewing the certification will enable you to meet the requirements of the CASS certification cycle.