1) Go to Setup, Session Catalog
2) Go to the Billing Code drop down box and select the Add-On CPT code you want to add from the list (example: 99354 or 99355)
3) Go to the Service Code field right above the Billing Code drop down and type in the Add-On CPT code you selected in the step above
4) Go to the Description field and enter a description for the code you are adding - Ex. Add On code for Initial Intake
5) Go to the Cost Per Unit field below the Description field and enter the cost
6) Go to the Mins Per Unit field all the way to the right and enter the minutes
7) Click Add New
8) Click the A1 button on the session that you want to add the Add-On CPT code to
9) Go to the CPT Code field and click the magnifing glass
10) Checkmark the Add-On CPT code, enter the number of units and then click Submit at the bottom
11) Notice the Add-On CPT code was added
Dislaimer: Codes in this article are examples only. For mental health professionals, the 99355 is almost always billed with 90837 or 90847. In addition, the first amount of extra time must be billed with 99354. Only if both 90837/90847 and 99354 have been appropriately billed can the extra time be billed with 99355. 99355 cannot be billed without 99354. Until the sessions reach an appropriate length you cannot bill 99355. Make sure to document the time spent to ensure you can bill 99355.