Is there a way to automatically add a percentage to a clients invoices if they choose to pay them using a credit card?

You can add a percentage fee to invoices for credit card payments, but this feature can't be applied automatically, csenek.

You'll need to create a service item and manually add it to the invoice. Here's how to do it:

1. Navigate to the Sales menu and choose Product & Service.
2. Click on New, then select Service.
   
   
3. Enter the name of your service item. (Example CC Fee)
4. Select the account you'd use to track the processing fees.
5. Click Save and Close.
   
   

Once done, add the credit card fee as a line item on the invoice.

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.
   
   

For step-by-step instructions, check this article: Charge a service fee to customers in QuickBooks Online.

Let us know if you have other questions by adding a comment, and we're always here to assist. 

You're most welcome, csenek.
 
We're glad to know that my colleague's advice helped guide you through the process of adding a percentage for credit card payments.

If you have additional questions about other QuickBooks-related tasks, you can add them below or create a new thread on the Community page.