Thanks for posting here, @Koimarket. I'm here to provide information about the credit card processing fee in QuickBooks.

To clarify, are you referring to applying a credit card processing fee on your customer's invoices? If so, you have two ways to do this in QuickBooks. Follow along below to get this done right away.

The first option is to create a service item for the fee and include it on their invoices. For the detailed instructions, you can refer to the steps outlined by my colleague, KurtKyle_M. 

On the other hand, you can also look for a third-party connector app that can be integrated into the program to help add the processing fees. Please head to our QuickBooks Apps store to find one.

Then, to connect with our phone support team, you'll have to initiate a callback request or select the chat option. I also advised avoiding adding your contact information when posting here in the Community to prevent endangering your security and privacy. Below are the steps to reach out to them:

1. Go to the Help menu and click the Search tab.
2. Next, select the Contact us button.
3. From there, enter a brief description of your concern (example: Charging a credit card fee in QuickBooks). Then, click Continue.
4. Then, choose either Chat or Callback.

Once everything is fine, your next steps is to collect customer's payments and record it in QuickBooks. For guidance, feel free to check this article: Record invoice payments in QuickBooks Online.

Please get back here in this thread if you have any follow-ups about credit card fees. I'd also appreciate it if you can add updates on how the recommendation goes. I'm just around the corner and ready to help whenever needed. Have a good one and take care.