The Coding Accuracy Support System (CASS) is a process and system implemented by the United States Postal Service (USPS) to improve the accuracy of address-matching software. It is designed to ensure that mail is properly addressed, reducing the likelihood of errors, undeliverable mail, and associated costs.

The CASS process involves the following steps:

1. Address Verification: CASS-certified software compares the address provided with a standardized address database maintained by the USPS. It verifies the accuracy, completeness, and proper format of the address.

2. Standardization: If any inconsistencies or errors are detected in the address, the software standardizes it according to USPS guidelines. This includes formatting the address elements (such as street name, city, state, ZIP code) correctly and applying standardized abbreviations.

3. ZIP+4 Code Appending: The software assigns the correct ZIP+4 code to the address, which further enhances mail sorting and delivery accuracy.

4. Delivery Point Validation: CASS-certified software also validates the delivery point of an address, ensuring that it corresponds to an actual USPS delivery location.

By utilizing CASS-certified software, businesses and mailers can ensure that their addresses are accurate and meet USPS requirements. This leads to improved deliverability rates, reduced undeliverable mail, and enhanced efficiency in mail processing.