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What is CASS?

By 5 July 2023April 15th, 2024No Comments
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What is CASS?

The Coding Accuracy Support System or CASS is a name that you should be familiar with if you run a business that regularly sends bulk direct mails to your customers/employees. The CASS is a tool that USPS created for ensuring that the software tapping into USPS’s official postal address database is accurate.

cass certified standard mails

Although several professional services, including mailers, service bureaus, and software vendors who utilize the USPS’s official postal address database, it is predominantly being used for address verification/validation. These professional services tap into the USPS database so that the address or addresses on their own database can be checked against the USPS database to update or cross-check their addresses.

What is a CASS Certified Service Provider?

CASS provides USPS to certify these service providers to let their customers know that the response they receive from one of these service providers is accurate and meets the USPS standards. In other words, CASS certification gives you a sure-shot way of verifying an address or group of addresses to be existing and deliverable. If a service provider is CASS certified, you can be sure that the said service provider meets the USPS's standard satisfactorily. That’s not all that a CASS certification means to a service provider.

A CASS-certified service provider guarantees that you would at the very least be submitted with missing information of the addresses you have provided to them in your address database. The addresses thus filled are then standardized and updated. This is the least you can expect from a CASS-certified service provider. Many advanced and user-friendly services such as PostGrid goes a step further by correcting the typos in the addresses you have provided and proceed to validate them by cross-checking the addresses with USPS’s official address database.

Before a service provider can be certified by CASS, they must first show they use Delivery Point Validation (DPV) and Locatable Address Conversion System (LACS) on their software for checking the addresses.

Understanding the CASS System

As we have discussed, CASS is basically a system that determines whether a service provider or a private party software is qualified to be a specialized software to process addresses and check them against USPS's official postal address database. The CASS system makes it possible for individuals as well as businesses to evaluate and measure the accuracy of the address verification carried out by a software provider. This helps you choose a more reliable service provider for your address verification or standardization requirements as the CASS-certified ones have already been tried and tested by the USPS. In effect, this means that the direct mails you send to the address that you have obtained through a CASS-certified service provider are most likely to reach their destination.

That being said, there still remains a lot of confusion around many people’s heads regarding CASS because “CASS” is often a word that is thrown around when talking about “CASS certification” and “CASS processing.” Although both of them are a crucial part of the CASS system, they are actually applicable to you more directly than you might think. Below we discuss the CASS system in depth and the various terminologies involved in the CASS system to better understand how the CASS system works and how each of them is relevant to you as a business.

CASS Certification

CASS certification implies that the service/software provider has qualified through the USPS's quality control tests, including the subject of standardization and validation of the addresses. Any company or organization that wishes to test the efficiency or accuracy of their address standardization and address validation through their software can subject it to USPS's quality tests for the CASS certification.

Sometimes these organizations or companies may have to subject their address verification tool for CASS certification tests every year. Once the organization/company feels that their software is ready to undergo the USPS CASS certification test, they can submit the same for review. Once submitted to USPS for review, the USPS checks the software to see whether it meets the standards set by USPS regarding the address standardization and address validation process.

Once the test is completed, USPS gives you a yes/no answer regarding the CASS certification. PostGrid is a perfect example of CASS-certified address verification software, and it even comes with a dedicated address verification API that can be integrated into your business’s website for easy and streamlined CASS address verification.

Requirements for CASS Certification

For an address verification software to qualify for CASS certification, it only needs to meet two simple requirements: to use both Delivery Point Validation (DPV) and Locatable Address Conversion System (LACS). Most Americans are familiar with both of these terms, DPV and LACS, even if they may not know what it exactly is. DPV or Delivery Point Validation, as the name suggests, checks whether the USPS can/will deliver to the specific doorstep or door number of a given address. The DPV is perhaps the most accurate and efficient form of address validation as it narrows down to the doorstep of the addressee. It is important to note this as anything lesser is not acceptable by the USPS standards.

Beyond the DPV, the USPS also demands the use of the LACS: Locatable Address Conversion System in the address verification software before it can be given a CASS certification. The LACS is an address database maintained by the 911 emergency services. The LACS ensures to find the person's location easily if he/she requires emergency service. What is special about LACS is that they keep track of the updated addresses to be matched with a national standard that is employed to make it easier to find the locations in an emergency. For the software to get CASS-certified, it must, at the very least, be able to refer to the LACS system when performing an address verification process. The USPS also prefers that addresses be updated to its latest version contained in LACS to ensure the process's accuracy.

CASS Processing

Now that we have a fair understanding of CASS, we can move on to the aspects involved in CASS processing. CASS processing refers to the process that takes place when a CASS-certified software runs an address through it for verification. Although each service provider indeed uses its own specific process, certain aspects of the process remain the same or common to all CASS processing.

There are mainly three major parts to the CASS processing that must be mentioned here, which includes:

  • Address Standardization
  • Address Update
  • Address Validation

Address Standardization

Before we can move on to any other steps involved in address verification, we must first standardize our address. The standardization process is carried out even before list duplication or gathering supplemental information. The purpose of address standardization is to clean up the data and present it in an understandable way for easy organization. The address standardization process changes the address that you have provided to comply with the USPS postal standards.

The first step in address standardization is to have the address put in the right format, as shown below.

house number, street name
city, state ZIP Code

In this stage, the addressee line is ignored as it is irrelevant at this stage. Once that is done, accurate abbreviations are added. For example, 1408 Lombard Street changes to Lombard St. After the abbreviations, the address is checked for spelling errors and typos, which are promptly corrected by the service provider’s software. The error could be anything from mistakes in designating the street, lane, road, etc. At this stage, any missing piece of information that can be deducted from the information that is already available from the address is filled in. The ZIP codes are generally filled in like this, but it is only possible if the street level and the city/state-level data are available and accounted for in the address that was initially provided.

It is crucial that you understand that the missing piece of information can only be filled by the software if there is a way to infer the available data. For example, PostGrid is an advanced tool used for CASS address verification that can easily fill in the missing details so long as there is enough data available for inferring it. However, neither the street name nor the house number of an address can be inferred from the data available as there is simply no way of figuring out the address they are missing. So basically, the address standardization process cleans, corrects, and completes the address fed into the software. Once the standardization is complete, we can proceed to the next stage of CASS address verification.

Address Update

As we all know, addresses sometimes change, and hence a CASS-certified system such as PostGrid will reference LACS during the process of address verification. The LACS, the address database used for providing 911 emergency services, is updated regularly for safety reasons. The unique nature of the addresses in LACS was implemented after responding to emergencies was made difficult by the individuality of the address system that was initially in use. As the address system at the time was hindering the emergency services, we came up with a solution to standardize the assigning of addresses. This standardization process ensured that the addresses were unique by using numbers, odd-even systems, and other similar methods. Even the old addresses were changed and updated to meet the new standards. As a result of the standardization, the addresses (for new buildings) are assigned according to their location and street to provide a more organized way for implementing LACS and providing emergency services.

However, the new system did have some drawbacks because changing the address also meant that it could potentially mess up the mail delivery. Sometimes the address would get changed just because the house was on the wrong side of the street, and the addressee may end up not getting their mails delivered to them. The LACS is responsible for tracking the modernized or changed addresses across the country and have them reflected on their database. This database can be accessed and used for cross-checking the addresses, and in case the address in question is one that has to undergo a change or modernization, then the mail can be routed over to the new address. CASS-certified systems such as PostGrid checks the addresses against LACS to make sure that the address provided is the correct one and whether it has been updated to a new address.

However, you must not mistake LACS with NCOA or National Change of Address. The NCOA is a database that keeps track of forwarded addresses, which is completely different from LACS. The LACS may reflect addresses that have been changed without the address's physical location staying the same. In contrast, NCOA contains information on addresses of people who have moved from one place to another. You can have your mails forwarded to you by the USPS by filling in a form or applying online stating your identity, your current location, and the location you are moving to. This ensures that your postal mails reach you to the new address even if you’ve relocated. That being said, not everyone chooses to have their postal mails forwarded when they move, and hence it is not always accurate.

Furthermore, these forwarding addresses come with a shelf life after which the misaddressed postal mails are stopped from being shipped to you. This makes NCOA your most reliable source for keeping track of where someone lives. A key difference between NCOA and LACS is that while the former keeps track of the “who” of the address, the latter keeps track of the “where” of the address. Furthermore, the LACS data is a much more reliable one than that of NCOA. This is why most of the address validation providers do not use the NCOA data. Whereas the LACS data is reliable and regularly updated, making it the obvious choice for address validation software.

As far as the address update process is concerned, in the event that there is a change in the address fed into the address verification software, it is updated to the most recent one available as recorded in the LACS database. Although rare, some providers choose not to update the address and instead provide you with the latest address paired with the original one. However, this is a practice that is often frowned upon, and it is highly unlikely you will have to deal with it if you are using an advanced solution such as PostGrid. Apart from this, every CASS-certified provider will be able to provide you with an accurate address database, including updated ZIP+4 codes for the delivery point.

Address Validation

Address validation, also known as address verification, is a method that allows you to determine whether an address is real or not. The validation process is carried out by comparing the updated address against an authoritative address database. It checks whether the given address is already present on the database, and if it is, then the address is classified to be real and active. This implies that the said address is real and that it is occupied and signed up for receiving postal mails from USPS. And if the given address does not have a match, then it is treated as “invalid,” implying that the address is either unreal or undeliverable.

But, address verification is not always so straightforward. There is a varying level of accuracy in address validation depending on the service provider you’ve chosen for your business. Let’s take the example of the address validation offered by USPS. The USPS address validation only offers basic features that only allow you to check if a given street name is from a particular city and check if the given house number belongs within the given street's proper range.

To get a complete picture, consider this if, according to USPS, Lombard street has a house number range of 401 to 499, and the address you’ve fed into the USPS address validation system has an address with 469, which does not have an actual physical structure bearing the 469 address. In this situation, the USPS system will still validate the address as it falls in the valid house number range. CASS-certified software like PostGrid addresses this problem.
Advanced address verification tools like PostGrid goes a step further by checking the actual delivery address or destination, including the door number. This advanced method of address validation is also termed Delivery Point Validation (DPV). We check the final address with USPS and see whether it is a deliverable one or not. Only after DPV does USPS allow PostGrid to add the ZIP+4 code of an address, and the DPV also standardizes the addresses before having them checked to give you accurate and clean data.

Furthermore, address validation is also possible to be carried out on the international addresses as well. Like the address verification process done with USPS, the international addresses are also compared or checked against the official postal address database of that country, such as the Royal Mail in the UK for UK addresses. As far as the postal mails sent inside or within the US are concerned, the United States Postal Service, USPS, has the foremost authority to validate a US address most accurately. The best way to do this is through an advanced CASS-certified tool like PostGrid.

Why Use CASS-Certified Address Verification?

Accuracy is the number one reason why you must use a CASS-certified address verification for your business needs. But, that’s not all that a CASS-certified address verification tool can do for you. Since the CASS-certified providers present you with addresses after referencing USPS databases, it is highly reliable, meaning that you can be sure that the postal mail will reach the addressee. The fact that CASS is a sanctioned system directly from the USPS only adds to its trustworthiness and reliability. Furthermore, CASS address verification covers everything from cleaning your address database to making it well organized and updated for your business needs.

As a result, CASS address correction enables you to keep away from bad data and avoid any unnecessary utilization of resources. In doing so, CASS address verification saves you not just money but also time and workforce, which can now be utilized for more significant tasks at your company. You can also save money on “workshare discounts,” which can be availed for sending out bulk postal mails. As the name suggests, work-sharing involves you presorting the mails or even adding the necessary barcodes to take some pressure off the USPS employees. Furthermore, to qualify for this discount, it is also necessary that you use a CASS address verification process.

Using a CASS-certified provider means standardizing, correcting, and checking the addresses, which further serves to help speed up the process at USPS. Everything you do, using a CASS address validation system in one way or another, serves to reduce the work pressure on the USPS employees. As an appreciation for your effort and shared workload, USPS rewards you with a discount. You can also employ advanced solutions like PostGrid to fully automate your direct mails from CASS address verification to sending out print mails.


The CASS or Coding Accuracy Support System was created for the sole purpose of providing an easier and accurate way of sending posting mails in the US through USPS. CASS has become somewhat of a hallmark for quality service when it comes to postal mail and address verification. That being said, it does not necessarily mean that all CASS-certified software is of the same quality or capability. While some offer the basic capabilities of CASS address verification, some others go a step further, like PostGrid, which accurately verifies your address and automatically updates and corrects typos and more.

Similarly, many CASS-certified providers offer the same services but with limited flexibility like individual or copy-paste format of address verification. On the other hand, we have advanced systems like PostGrid, which lets you bulk CASS address validation and automate the entire process, including sending out print mails to the verified addresses. Furthermore, you can employ the address verification API of CASS-certified service providers like PostGrid to access their CASS-certified services easily. Depending on your business’s unique requirements, you can choose which services you require from an advanced CASS-certified system like PostGrid to streamline your business operations.

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