1. Open the Job Detail page. Under the task tab you will see a "Billing Rate" dropdown next to Planned Duration.
2. By default, for a new task that has not been scheduled and assigned to a mechanic, your Default rate is applied. To change the rate for the task, click on the dropdown.
3. Select the rate you want from the dropdown
Use THIS article if you want to find out how to add a new rate
4. When a task has been scheduled, the rate for your mechanic is applied. Open the list of rates to see this option in the drop down list.
5. When you select a different rate, the cost of the task is recalculated using the new rate that you selected. For example, if you assign a rate of "Insurance", that rate will be applied to the work irrespective of which mechanic you schedule the task to.
The cost of the job automatically recalculates every time a new rate is applied.
Your garage has a Default Rate. When a task is scheduled to a mechanic, the Default Rate is replaced with the rate of the mechanic. If you unschedule the task, the Default Rate is used. Unless you specifically override Default Rate with another selected rate (e.g a new rate that you created for Insurance work), Default Rate is used to calculate invoices.