The 2026 Guide to USPS CASS and NCOA Certification

In the world of bulk mailing and logistics, data quality isn't just a "nice to have"—it is a financial necessity. Understanding CASS and NCOA is the difference between a successful campaign and thousands of dollars in wasted postage.

What is CASS Certification?

CASS stands for Coding Accuracy Support System. It is a process used by the United States Postal Service (USPS) to verify that an address is technically "mailable."

ZIP+4 Codes: Adds the correct 4-digit extension to the 5-digit ZIP.
DPV Validation: Confirms the specific suite or house exists.
Standardization: Formats addresses to USPS specs.

What is NCOA Link?

While CASS checks if an address exists, NCOA confirms that the recipient still lives there by checking the USPS database of people who have moved in the last 48 months.

Why Your Business Needs Both

Without CASS, your mail might have the wrong ZIP code and get lost. Without NCOA, your mail might reach the right house, but the wrong person. Combining these ensures you aren't paying to ship "ghost mail."

Start Cleaning Your Data

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