AVS Mismatch Explained: What Is It and How Do I Fix It?

If you’ve ever seen a transaction declined due to an “AVS mismatch,” it means the billing address didn’t match what the cardholder’s bank has on file. Here’s what it means and how to fix it fast.

What Is AVS?

AVS stands for Address Verification System. It’s a fraud prevention tool used by payment processors to verify that the billing address provided by the customer matches the one on file with their card issuer.

If there’s a mismatch in the ZIP code or street number, the transaction may be declined or flagged as suspicious — especially for high-risk merchants.

What Causes an AVS Mismatch?

Customer entered the wrong billing ZIP code
Auto-fill or saved address errors during checkout
Recent address change that hasn’t updated with the card issuer
Mismatch between your checkout form and how the bank stores the data (e.g. “St.” vs “Street”)
Fraudulent attempt with a stolen card

How to Fix an AVS Mismatch

Double-check address input: Ask your customer to confirm they’re using the billing address linked to their card.
Use AVS-friendly gateways: Some processors offer more flexible AVS settings that reduce false declines.
Customize your risk filters: In Authorize.Net or NMI, you can decide whether to block or allow mismatched AVS codes.
Switch processors: If you’re getting blocked constantly, it may be your processor being overly strict.

Common AVS Codes and What They Mean

Y: Full match (address and ZIP)
Z: ZIP matches, address does not
A: Address matches, ZIP does not
N: No match
R: System unavailable or timeout

If you’re seeing mostly “Z” or “A” responses and still getting declines, it’s time to reconfigure your AVS settings or talk to your provider.