If any patient has prepaid for services, it means that they'll have a credit on their account:

This credit can be used towards the payment of any future service. 

This article will walk you through how to "pay" an invoice using that credit!

Create an invoice for the patient. When you're in the "enter payment" stage, do not enter an amount in the "Payment source" field! Instead, you'll notice that the amount of credit is listed, and it will also say how much credit is being applied:

By default, Cliniko will attempt to apply a portion of the credit to the entire balance. For example, if the invoice is for $50, and there is at least $50 of credit, that entire credit would be used to "pay" the invoice.

Again, if the invoice is to be paid completely by credit, do not enter anything into the "Payment source" fields!

Before saving the payment, you can confirm how much credit is being used to pay for the invoice:

Save that payment, and you'll now see that the invoice is "paid" (and closed) with account credit:

If you click into the payment, you'll see that the total payment is $0, and $0.00 was applied to invoices:

This is because the actual payment (the prepayment from earlier) was where money was exchanged. At this point, you're simply allocating a portion of that credit to an open invoice!

The patient will now have a lower balance of credit than they did earlier, as well—again, because a portion of this credit (or perhaps the entire amount) was used to "pay" for an invoice.

You'll want to repeat the above steps any time you need to "pay" an invoice with account credit.