Department split on Payroll Analysis

It would be helpful if the payroll analysis report is able to split one employees pay details according to the department cost split. For example we have an employee that works for two different clients and we want to show this split via the department codes on the employees profile. However the only report that shows the breakdown of the department split is the Payrun Journal which doesn't provide a comprehensive report compared to the payroll analysis. We want the payroll system to be able to split the salary, NI, Pension etc accross the 2 departments.