Coding Accuracy Support System (CASS)

The Coding Accuracy Support System (CASS™) is a United States Postal Service® (USPS®) program that certifies the accuracy of address validation software. To qualify for certain postal discounts you must use software that is CASS Certified™ to assign ZIP Code™, ZIP + 4® codes, and delivery point barcodes to mail.

Makers of address validation software must pass a test designed by the USPS in order to have their software designated as CASS Certified™. CASS Certified™ software must pass tests of accuracy in the following areas:

  • Five-digit coding
  • ZIP + 4®/delivery point (DP) coding
  • Carrier route coding
  • Delivery Point Validation (DPV®)
  • Locatable Address Conversion System (LACSLink®)
  • Enhanced Line of Travel (eLOT®)
  • Residential Delivery Indicator (RDI™)

When you use a CASS Certified™ product, you are assured of the following minimum levels of accuracy:

Table 1. CASS Certification Levels

Certification Level

Required Accuracy Level

ZIP

98.5%

Carrier Route

98.5%

ZIP+4

98.5%

Delivery Point Barcode

100%

eLOT

100%

Perfect Addresses

100%