I have an employee payroll spreadsheet and I need a formula to show any difference between monthly net pay.

There is a unique ID for each employee in column A and the net pay amount is in column Q. I want the variance to be shown in column W.

E.g. Employee 19 had net pay of £1000 paid in August, this is shown in cell Q728, in July they were paid £1050, this is shown in cell Q678. In cell W728 I want it to say -£50.00.

I want to be able to track these difference each month. If in June they were paid £2000 cell W678 it should show a value of -£950.00. It needs to the vertical column for the last value. The date is in column C.