You can apply individual rates to a client. When you set a rate schedule, that rate schedule will be suggested automatically when invoices are created.
You can override this on a per-project basis in the project detail screen. The project's default rate schedule will then be suggested instead.
Setting a rate schedule from client profile
Navigate to the Client
Select the client you would like to apply the rate schedule to
Scrolled down to the billing section in the client's profile
Select the rate schedule from the drop-down menu
Save
Setting a rate schedule from the rate schedule
Navigate to Billing
Select Rate Schedules from the top tab bar
Choose the rate schedule that you want to apply to a Client
In the overview there is a clients section, click on this for a drop-down menu of all the Clients. These are divided into Clients without rate schedules and Clients with rate schedules.
Select the Client or Clients you want to use this rate schedule
Save