Welcome to the Community, Fivewildtrading.

I'll help you add a credit card processing fee to your invoices in QuickBooks Online.

While we can not do this automatically, follow the steps below to add a credit card processing fee to your invoice - you can create a service item and manually add it to the invoice. Alternatively, you can consider integrating a third-party app with your QuickBooks.

Here's how:

1. On the left navigational bar, go to Get paid and & pay tab.
2. Choose Product & Service.
3. Click on New, then select Service.
4. Enter the name of your service item. (Example CC Fee)
5. Select the account you'd use to track the processing fees.
6. Once done, click Save and Close.

Once done, add the credit card fee as an additional item on your invoice when charging your customers with the processing fee.

Here's how:

1. On the create invoice page, click Add line.
2. From the Product or Service drop-down column, choose the charge convenience fee you created.
3. Click Save and Close.

Here is an article you can refer to for the detailed steps: Manually add service fees to invoices in QuickBooks Online.

Let me know if you have questions about managing invoices in QuickBooks Online. I'm always here to help. Have a great day.