Incorrectly addressed mail is one of the major issues that the United States Postal Service has to deal with. It requires them to spend a significant amount of time sorting and delivering mail. This has an unwanted impact on cost and delivery time. To solve this issue, USPS came up with a standardized process called CASS, or Coding Accuracy Support System. Its aim is to make sure addresses follow standardization and formatting requirements.
The process basically validates addresses against a list provided by USPS. This list contains all deliverable addresses in the U.S. and USPS updates it quarterly.

CASS Certification

Now that we know what CASS is, let’s discuss how CASS works.

Actually, it is pretty straightforward. A CASS certified service bureau processes data in concordance with USPS standards. This means that the service:

  • Fills-in any missing information,
  • Standardizes the address,
  • Updates and validates it by checking if it’s in USPS’ database

It is important to note that, in order to meet CASS standards, you have to use DPV and LACS. Since there is a slight chance that you are unfamiliar with these acronyms, we’ll be briefly explaining them.


DPV, or Delivery Point Validation, checks against the USPS database to find out if an address is on file. If so, it means that USPS can deliver to the doorstep. An address that is not found in the database is considered “invalid” or is not receiving mail.


LACS, or Locatable Address Conversion System, it’s a system USPS created to help emergency services become more efficient. Before 911 was instituted any local government had the freedom to assign the addresses however they see fit. This made responding to emergencies unnecessarily difficult. Thus, the assignment of addresses was standardized throughout the country. But what happened to old addresses? They were simply updated to the new standard and LACS keep track of all these changes.

Now, let’s summarize what is CASS:

  • Correct addresses reduce the amount of unsorted and undeliverable mail.
  • To correct meet USPS standards, mailers have to put up more effort to determine the correct address to which the mailing should be delivered.
  • To speed up their workflow, mailers use specialized CASS software that is able to check if addresses are compliant with USPS requirements.

If you are a mailer, there is an important reason to use CASS software. You could qualify for discounted rates from the USPS! We’re going to talk about this a bit later.

CASS Processing

CASS processing is, in most cases, handled by dedicated software. The way it works is straightforward. First, the software standardizes addresses. Next, the application corrects and updates them. Lastly, the software validates each and every address against a database provided by the USPS. This database is always up to date.

Let’s delve into details and see what happens at each stage:

  • Standardization. This is always the first step. No validation or deduplication should happen before standardization. To standardize an address, the application processes each address and formats it according to CASS Standards. For example, the software replaces “#” with “APT”. If it finds missing information, a CASS-based software will fill it only if  it can be inferred from the available data.
  • Correction. All typos are corrected and missing ZIP+4 Codes are added.
  • Updating. The software compares the address against the latest USPS database and updates addresses that have changed
  • Validation. This is the last step. It assures that the mailing is deliverable by comparing the address with the latest USPS database

To conclude, CASS processing assures that USPS is going to deliver your mail. Also, it spots any missing information such as apartment number. Note that, CASS only checks if mail can be delivered to the provided address. It does not check the recipient’s name.

Reasons for CASS-Certified Address Processing

Of course, the most important reason to use CASS-based software is accuracy. USPS maintains CASS and the system relies on several different processes to assure address accuracy. No other alternative offer the same level of reliability. Say goodbye to returned mail.

Next, CASS processing greatly simplifies your workflows. You don’t have to import data from other sources. Since CASS provides everything you need, your database is always free of incorrect data and up to date.

Lastly, CASS can save you many if your organization sends mail in bulk. To qualify for discounts, it is not enough to do the presorting and add the barcodes. You also have to standardize, update, and validate the addresses according to CASS.


We hope that this blog posts answered the “What is CASS question”. By know, you should be aware that USPS put in place CASS  to ensure that addresses are accurate, up to date, and meet their standards.

WinPure Clean & Match Enterprise with USPS Address Validation adopts USPS standards and extracts all CASS fields. As we’ve seen, this could bring you significant benefits:

  • Once our software processes address data, you can get discounts on shipping.
  • You will reduce your bulk mailing costs while improving their accuracy and efficiency.
  • You will be able your customer’s experience by communicating more clearly and efficiently. There will be no undeliverable mails. Also, your mailing is  always going to be delivered on time

If you want to stay ahead of the competition, then come check out our WinPure Clean & Match Enterprise with Address Verification today!

Last Updated on 28th November 2020 by admin

By Andrei Popescu | December 24th, 2018 | Posted in Address Verification

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