CASS™ Certification


The Coding Accuracy Support System (CASS) enables the USPS to evaluate the accuracy of software that corrects and matches street addresses. 1

CASS™ Certification

A service provider that meets all of the stringent USPS accuracy requirements is CASS-Certified™.2 Only a CASS-Certified™ provider can provide the necessary documentation you will need to get bulk discounts on a mailing.

Why CASS-Certified™ vendors matter

Once an address has been cleaned up, standardized, and verified as deliverable, you can be nearly 100% sure that it will be delivered as expected.3 If you have the proper documentation (CASS™ Summary Report), the USPS will reward you for your address verification efforts by allowing you to pay a lower price for postage.

The USPS Form 3553 certifies to the post office that your mailing has been processed by our address verification service. The report must be generated by our automated process. Handwritten forms are not accepted by the post office. When you download your verified list, it will contain the form you need.

  1. CASS™ System, USPS <>
  2. Coding Accuracy Support System, Wikipedia <>
  3. Of course things like meteorites, volcanoes, or a loose pack of rabid dogs can still cause delays to postal delivery. But at least you can say you did your best.