Postal Terminology – CASS vs. NCOA. What’s the difference?

In order to maximize the delivery of your mail, minimize returned mail (which wastes both production and postage costs), keep your database up to date and receive the lowest postage rate, you should always run your list through a CASS and NCOA process. We hear these terms often. But what do they mean?


CASS – certifying the address information in your mailing list allows for automation-rate bulk mailings and USPS presort discounts. An important thing to note is that name-related data is NOT taken into consideration by CASS – it is only standardizing the address data. By processing your list to meet USPS regulations for address standardization, your mailing can qualify for the lowest possible postage rates. The CASS system improves the accuracy of the carrier route, five-digit zip codes, nine-digit zip codes (zip + 4), and delivery point barcode, improving the deliverability of your mail, and provides useful diagnostics for correcting errors. Let’s look at an example.

Your submitted address might look like this:



The CASS processing will change the address to this:


REDMOND, WA 98052-8300

Here the street and city name misspellings have been corrected; street suffix, ZIP code and ZIP+4 add-on have been added; and, in this case, the address was determined to be the location of a business. When we run a list through CASS and the address cannot be corrected, we receive a report stating that the address is Undeliverable As Addressed (UAA). We pull any such addresses from the mail file since it would simply be wasting money to produce and mail something that will not be delivered. To keep your list from having too many UAAs, we suggest that you run your entire file through an Address Resolution Service (ARS). ARS will not correct every address but our experience shows that between 30% and 40% can be fixed. Typically, running your list through ARS on an annual basis should be sufficient.


NCOA certification meets the move update requirement set forth by the United States Post Office. NCOA compares your mailing list to a database of over 160 million address changes filed by postal customers making a permanent change of address with the USPS over the past 48 months. Here, unlike CASS, the name AND address data is used to identify “hits” in the address change database. In fact, the address data should be CASS-certified before the NCOA process to get the most accurate results. Whenever a name and address from your database matches one of NCOA’s old addresses, we update your mailing list with the forwarding address and notify you when there is no address available. The NCOA update will:

  • Reduce undeliverable mail by providing the most current address information for matches made to the NCOALink file.
  • Prevent re-mailings after address corrections are received because the address correction is applied prior to the mailing.
  • Reduce mailer costs by reducing the number of undeliverable mail pieces by using most current address information.
  • Provides the opportunity for faster product/service marketing through accurate mail delivery.
  • Speed mail delivery by not having to reroute it from an old address to a new one.

Keep in mind that only 85% of individuals or families that move file a change of address form with the post office. So even when your list is processed through the NCOA database you can still receive returned mail. If you would like more information on these services, please email us at

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