Hello there, info1336.

Currently, the easiest way to include the Terms and Conditions to the invoices is to add them as Attachments.

1. Save the Terms and Conditions as a PDF file on your computer.
2. Open the invoice you want to review and scroll-down to the Attachments section.
3. Click the Attachments hyperlink or field.
4. Locate the PDF file of your Terms and Conditions.
5. Click Open and it will be added to your invoice.

To know more about attachments, you can use this link: Attachments in QuickBooks Online.

Feel free to get back to us if you need anything else. Have a great day!