Hi Carl
Have you thought about making your sequential number No Duplicates? You would also need VBA to do whatever you want if it is a duplicate.
John

I have done that, which is what inspired my question, I get a message that states, number already exists, Please change. But I would like access to automatically assign a new number. I am using "Left(CustomerName, 6)". If this happens I do not want users to just randomly change the Customer Code. I was thinking that maybe there could be some code that would just automatically change the last character to a number. Let's say the code (Chisum) received a message "Code Already exists, Please Change". In this case Access would just remove the last letter (m) and replace it with a 1 and return a new code of Chisu1. Or just add a number to the end and return a code of Chisum1. This would keep my customer code system uniform and prevent random changes. I could then display a message that said, "Your code has been modified because it was a dupliicate."

Is this what you are looking for. I use some basic validation in my example but the last letter is replaced by a number in the event of duplicate codes.

Thanks Kevin, I added to your tip jar. Works exactly as I need.

You're welcome and thanks.