Let me show you some options to make your customer responsible for the credit card transaction fee in QuickBooks Online (QBO), Potter.
Currently, QuickBooks Payments doesn't have a feature to charge customers directly for transaction or processing fees. As an alternative, you can
create a service item for the fees and manually add it to your invoice. Here's how:
- Go to the Gear icon, then choose Products and Services.
- Click on New, then select Service.
- Enter the name of your service item. (Example: Processing Fee).
- Select the account you'd use to track the processing fees.
- Once done, click Save and Close.
Once completed, add the processing fee as an additional item to your invoice to charge your customers.
Another option is to include the negative amounts for the fee along with your transactions when generating the
deposit. Here's how:
- From the Bank Deposit window, scroll down to the Add funds to this deposit section.
- Enter the fee as a line item.
- Choose from whom the fee was received in the Received From section.
- Select Bank Charges from the Account ▼ dropdown.
- Enter the amount fee as a negative number. For example, if the fee was US $5, enter –5.
- Review the deposit total with the bank fee. Once everything's good, click Save and close.

Additionally, you can read through this article that helps you learn more about the turnaround time to get your customer payments in your bank account:
Find out when QuickBooks Payments deposit customer payments.
On the other hand, here's a resource that you can follow when your customer has overpaid you:
Handle a customer credit or overpayment in QuickBooks Online. You can use the credit toward an invoice, refund the customer, or enter the overpayment as a tip in QuickBooks.
Feel free to mention me in the comment section if you have any other questions about assigning the transaction fee to the customer. I'll be around to further assist you, Potter.