Navigate to the Billing tab, then the Services icon.
Choose the Account you would like to add or edit codes and rates.
Select the black dropdown arrow on the Purpose field then choose the correct Purpose for that Code. For example, when you have a different base rate for a trip that is Dialysis, you would add the purpose in the Services grid to differentiate it from a typical Base charge.
Save any changes.
For more information about creating a purpose, click Here.