How can I create a Customer Order No. box on the Tax Invoice?

Hello there, @ian-paintspectio.

Thank you for posting here in the Community. I can help you create a Customer Order No. box on the tax invoice.

In QuickBooks Online, you have the option to configure the templates and add a custom field. You can go to the Custom form styles section and edit the tax invoice template.

Here's how:

1. Click the Gear icon in the upper-right corner.
2. Select Custom form styles.
3. Search for the template.
4. Press Edit below the Action column.
5. Go to the Content tab.
6. Click the pencil icon in the upper-right. 
7. Scroll down and select +Custom field. 
8. Add an extra field.
9. Hit Done. 

For additional reference, I've attached some articles you can use to customise the info on your forms, as well as importing invoice templates in QuickBooks:

• Customise invoices, quotes, and sales receipts in QuickBooks Online
• Import custom form styles for invoices or estimates

I'm only a few clicks away if you have any other questions. Wishing you and your business continued success.