Create a sent home pilicy, this is quite effective to me, and this will give you edge to let these employee know how serious you are in implementing company policy.
GRACE PERIOD, TARDINESS & SENT HOME
Please be informed of the meaning and difference of the following;
• Grace Period
o An amount of extra time given to someone to come to work but still considered late (e.g. 8:15 – 8:25, the time between 8:15 to 8:25 is the grace period).
• Tardiness
o Delayed beyond the expected, proper time or schedule of work (e.g. 8:15 – 8:25, the time between 8:15 to 8:25 is the time considered late).
• Sent Home
o A process to sent home those who came after the given grace period (e.g. those who came after 8:25am)
These are policies that have existed which needed to re-publish by Human Resource Department for everyone’s awareness. Those employees who will commit beyond such will received corresponding memo for negligence on attendance.