How to highlight lateness?

Hi,

I have a MS access database consisting of the following fields:

First Name
Surname
Employee number
Date
Actual start time
Required start time

All the employees start at either 8,8.15,8.30,8.45 or 9am.

I am able to monitor what time they start but how do I highlight when they are late in Access? Basically if someone is due to start at 9am (required start time) and they arrive at 9.03am (Actual start time). How to I make the "Actual start time" highlighted? Also, if I want a query button to press to see who was late on a specific day what type of code would I use??