How the 10% works
Take the hourly rate for the day (daily rate ÷ 8, times any holiday or rest-day multiplier already in effect), add 10% of that rate for each hour worked between 10 PM and 6 AM, on top of the base pay for those hours. It stacks with overtime too: a night OT hour earns the OT rate plus 10% of the OT rate. For a 24/7 guard force this premium recurs every single night — small per hour, large per payroll, and the first thing to leak in a manual computation.