If you have multiple staff members (including contract staff) working on a case (project), you can easily find out different billable amounts for each staff member. This data can be useful if your staff members are paid a percentage of what they bill to clients. 
To obtain a staffwise billing report, click on "Settings/Reports" -> "Staffwise Billing Report." On the righ side panel, select a specific client/case or select all. Clicking on "Generate Report" will create an excelsheet. Having this report in Excel format will enable you to perform other accounting tasks on the sheet.