Thanks for joining the thread and sharing the information provided by your accountant, @GoJu.
I'm here to share insights on how you can handle your invoice payments.
Beforehand, I'd like to confirm that what your accountant mentioned aligns with standard practices for handling sales transactions in QuickBooks.
In QuickBooks, creating an invoice signifies a sale and the amount that a customer owes you. Once you receive payment, you can mark it as paid within QuickBooks. It's important to note that it's not necessary to enter a separate receipt for the payment as it would result in recording the income twice.
See this article for more details: Difference between an invoice and a receipt?
Additionally, you can check out this article for more details on handling invoice payments, especially if you want to record partial payments in QuickBooks: Record invoice payments in QuickBooks Online.
Please keep me posted if you have follow-up questions about managing invoices and their payments in QuickBooks. I'm always around to help.