With the SimplePractice billing system, your client's balance will only increase when an invoice is generated. If an invoice has not been generated for one or more sessions, it's possible for a credit to show up in the client's profile where there should be none.
Here is an example of a session for which an invoice has not been generated. You can see that there is an "Uninvoiced Amount."
If we add a $150 payment, the credit will appear:
To resolve a client credit, click "Uninvoiced" under the "At-A-Glance" section. You can quickly generate an invoice for any uninvoiced sessions by just clicking the "Uninvoiced" link. You will be asked to confirm this:
After you click "OK", you will see the uninvoiced amount applied against the client's balance. Because there was already a credit, if the credit equals the amount of the invoice, the invoice will indicate that it's "Paid".
A check of the At-A-Glance section confirms that there is no longer an "Uninvoiced" amount, and the client's balance is no longer a credit.