How Does an AVS Check Work?With an AVS Check, Only the Numbers Count

Harlan Hutson | August 4, 2025 | 2 min read

How Address Verification Works: The Ins & Outs of AVS Checks

Given that it’s called the “Address Verification Service,” you might assume that AVS checks the whole nine yards — the street name, street numbers, zip code, and unit number — when verifying an address. It's a reasonable assumption… but not the correct one.

When checking for a match, an AVS disregards the letters in the address provided, only comparing the numbers to the address on file. In this article, we take a deeper look at how an AVS check works and examine why this verification quirk exists.

How Does an AVS Check Work?

The Address Verification System works basically as follows:

The buyer — not necessarily the cardholder or an authorized party — enters their address at checkout and submits the order.
The address information is transmitted to the processor, where the given address is compared to the address the cardholder has on file with the issuer. Note that only numeric values (street number, box number, zip code, etc.) are compared.
A response code is generated based on one of six basic conditions: full match, no match, partial match, zip code match, data unavailable, or international address. The entire process is seamless and takes mere seconds.
Based on the response code, you can decide to either accept or reject the transaction. This decision should take into account indicators generated by other fraud detection tools as well.

Address Verification Service can tell you that an order may — or may not — be a case of fraud. You’ll need to use your best judgment and decide whether to proceed with the transaction on your own, though.

You may choose to require additional information from the customer to confirm their identity. You can also set up accept/decline parameters to automatically trigger a decline if certain codes are returned. The latter practice is not without its risks, however, as we’ll see later on.

Why Does AVS Only Examine Numeric Characters?

To reduce complexity and lighten the computational load, an AVS check only evaluates the numbers in a billing address. Anything with letters, like the street and city name, are left unverified.

The reason for this is simplicity. Numbers only range from 0 to 10, and the way they are presented are fairly standardized. For example, in the United States, street numbers have between one and five digits, and zip codes are always five or nine digits long.

On the other hand, there can be many variations in street names. A street type like “Avenue” or “Street” can be spelled in its full form or abbreviated as “Ave.” or “St.,” respectively. Likewise, a cardinal direction like “Northwest” or “South” can be abbreviated “NW” or “S,” respectively.

Limiting an AVS check to the parts of an address that are less ambiguous makes the verification process faster and simpler. However, this shortcut can also result in occasional errors, which we’ll talk about later.