I'll share some information on what to do if your credit card transactions fail because of a zip code error.

This error usually occurs when you attempt to process a payment using a billing address outside the U.S. They may have a ZIP code (or Province code) that includes characters that do not meet the U.S. 5-digit standard.

Card issuing entities typically inform their cardholders about how credit card transactions work in the United States, including the occurrence of an invalid zip code error. 

Since you've encountered a zip code error, I suggest you reach out to your card issuing bank to determine whether there are any alternatives for using their international card with U.S.-based businesses that require a 5-digit numeric zip code.

You can utilize this article for future reference: Fix customers' declined credit card payments.

Feel free to post here again if you have further QuickBooks-related concerns. We are available 24/7 to lend a hand with each of your queries. Stay safe!