I've used an invoice number twice. how do I find the first time it's used?

Hi kaygaffy,

You can run the Invoice List report to be able to see the invoices and invoice numbers used in your sales forms. Here's how:

1. Click on the Reports tab.
2. Search Invoice List.
3. Set the Report period to All dates.
4. Click on Run report.

Once done, run through the invoice number column to verify. From here you can check any duplicate or used invoice numbers. To edit an invoice and the invoice:

1. Open the invoice.
2. Scroll down at the bottom and click More.
3. Choose to Delete if it’s a duplicate invoice.
4. Edit if it’s only a duplicate invoice number, then click Save.

To avoid duplicate in the future, we can set a way to make sure there are no duplicates once you create the invoice. Please follow the steps below:

1. Select the Gear icon.
2. Choose Account and Settings, then click Advanced.
3. Under Other preferences, put a check-mark on the tick boxes that say:  

• Warn if duplicate check number is used
• Warn if duplicate bill number is used
• Warn if duplicate journal number is used
   

Once done, QuickBooks will notify you every time you make an invoice, to prevent using duplicate numbers.

Post again in the Community if you have further concerns with invoices. I'll be around to  help you.