Can I add PO numbers to my invoices?

I appreciate you for adding your first post here in the Community, Ian.

Yes, you can add PO numbers to your invoices in QuickBooks Online (QBO). I'm here to share with you the details. At this time, you can add the PO numbers through the Description section of your invoices, or you can use a custom field (if you are using the essentials or plus package). To add a custom field, I'm adding this article as your reference: How to add custom fields to sales forms and purchase orders.

Let me know if you have any other questions while handling your forms and sales transactions in QBO by adding a comment below. I'm always here to help. Have a good one!