CASS Certification Process
The formal USPS testing procedure that software vendors must pass to certify their address-matching products for use in qualifying mailings for automation discounts.
The CASS certification process requires software vendors to submit their address-matching engine to the USPS National Customer Support Center for testing against a standardized dataset. The software must correctly assign ZIP+4 codes and carrier route codes to a minimum percentage of test addresses to pass certification.
Certification is valid for a limited period (typically 12 months), after which the software must be re-tested against an updated address database. This ensures that certified software stays current with USPS address changes, new construction, and boundary adjustments.
The CASS cycle drives the entire address quality ecosystem: software vendors compete on match rates and processing speed, mailers rely on certified software to earn postage discounts, and the USPS benefits from cleaner addresses that improve automated processing efficiency.