How do I prevent duplicate invoices on ONQB when exporting?I know its in settings/advanced/other preferences except I dont have Warn if duplicate Invoice number is used?

Hi benetti,

Thanks for posting in the Community!

Let's check your company settings to see if you've turned on the Custom transaction numbers for your sales form. Here's how:

1. Click on the Settings icon.
2. Click on Account & Settings, and click on the Sales tab.
3. Locate Sales form content, and check Custom transaction numbers if it's turned on or not.
4. Click Save and Done.

Turning on the Custom transaction numbers helps you avoid getting duplicate invoice numbers. You can check this article to learn more about Add custom transaction numbers to sales forms in QuickBooks Online and Find duplicate transaction numbers in QuickBooks Online.

Message us back if you have more questions about QuickBooks Online!