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How to Fix Duplicate Invoice Numbers

Encounter the "Invoice number already in use" error? Learn how to resolve it by updating draft invoice numbers.

Melissa Schaefers avatar
Written by Melissa Schaefers
Updated over 3 months ago

This error typically happens if you undo invoices back to drafts and submit other invoices in the meantime. Quickbooks will retain the "used" invoice number in their system so when you attempt to resubmit the invoice, it will flag an error.

It can also be the result of someone setting a number manually on a draft invoice or an invoice in QuickBooks and causing the sequence to pick up from there.


Fix 1: Set a new number on the draft


The way to fix it is to set the draft to a number higher than what you have in QuickBooks already.

Note: Make sure it's higher than the highest invoice number in QuickBooks so you don't run into the issue again!

You can set the new number here on the draft invoice:


Fix 2: Turn off custom transaction numbers


NOTE: Turning off Custom Transaction Numbers in Quickbooks will allow multiple invoices to share the same invoice number. Only use this option if it fits your business needs.

Here are the steps in QuickBooks Online:

  1. Click the gear βš™ icon in upper right corner

  2. Click "Account Settings" in the upper left column

  3. Click "Sales" in left column

  4. Click into "Sales form content"

  5. Turn off "Custom transaction numbers."

  6. Click "Save"

  7. Click "Done"

If you have any further issues, please reach out to our

Customer Success and Support team!

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