Reference date

[Keith166]

I have StartDate and EndDate fileds where I enter the date and time the employee starts and finishes his shift (in dddd dd mmmm yyyy hh:nn AM/PM format). However there is a penalty issue that starts at 7.00 PM.
How do I set up a non changing reference for 7.00 PM that I can reference to make a calculation.
For example I need to calculate penalties for when the employee works hours past 7.00 cutoff time.

I would appreciate any assistance to solve this problem

Thanks