USPS CASS (Coding Accuracy Support System)

USPS CASS (Coding Accuracy Support System) is a certification tool used by the United States Postal Service to verify the accuracy of address information on mailpieces. It standardizes and corrects addresses to ensure they conform to USPS mailing standards, which helps improve delivery efficiency and reduce misdeliveries. When a mailer runs addresses through CASS-certified software, it identifies and corrects errors, verifies ZIP codes, and ensures addresses are formatted correctly. This process helps streamline mail processing, lowers postage costs, and increases the likelihood of timely delivery.