If your client is responsible for paying a co-insurance (as opposed to a co-pay) that can be managed through SimplePractice as well.
Be sure that you have set your client's billing type to "Insurance Pays Me" and you have recorded all the client's insurance information on his/her Billing & Insurance tab. On the Billing & Insurance tab enter the estimated co-insurance amount in the "Co-Pay" field. This amount will be charged to the client until you revise it later.
After the claim for the client's sessions are processed, the insurance company will send you an EOB (or electronic payment report) along with the reimbursement check. This EOB will tell you exactly what the client's co-insurance responsibility is for each session.
You will enter this co-insurance information when you record the insurance payment to SimplePractice. If you're not familiar with adding an insurance payment, read this article: Adding a payment from an Insurance Company.
When you record the insurance payment to SimplePractice, update the Co-Pay amount to reflect the client's co-insurance responsibility.
When you update the Co-Pay field and allocate the insurance reimbursement, this will update the client's balance as well as the insurance company's balance. When you return to the client's Billing Details page, you will see the updated co-insurance amount indicated on the session and the client's overall balance due will update.
Note: Insurance payments and co-insurance amounts will be automatically recorded if the payer offers online payment reports and your enrollment has been accepted for these reports. Learn more about payment report enrollment here: Enrollment for Payment Reports.