If you've found an invoice with no transaction number assigned, this is likely a rare occurrence. If you want to manually assign a transaction number to the invoice follow the steps below.
Please Note: It is important that you do not create a duplicate transaction number during this process. See below for more information.
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Manually Add Transaction Number
1. Go to your QuickBooks Online account and take note of the most recent invoice transaction number.
2. Enable custom transaction numbers:
- Click on the gear icon (top right) and select "Account and Settings"
- Go to the "Sales" tab.
- In the "Sales Form Content" section, change the "Custom Transaction Numbers" setting to ON.
3. Find, open, and adjust the invoice(s) that are missing a transaction number.
4. Create a new invoice and add a transaction number that is one number higher than the most recent number (noted in step #1).
5. Turn custom transaction numbers back off - see step #2 above, but change the setting to OFF.
6. Create a new invoice and make sure that the number starts in the correct place.
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More Information
Generally we do not recommend custom transaction numbers. To learn more about why, please see the Custom Transaction Numbers in QuickBooks article.