Depending on the company policy, there are 3 common methods:
1. Fixed number of days, ie. 26 days [must, for employees earning less than RM 2,000]
2. Calendar days, eg. 31 days for August
3. Working days in calendar month, eg. 22 days including public holidays, Mon - Fri
The most common method is where companies fix the number of days at 26 since there won't be any chances of dispute.
Example: Azim has a basic salary of RM 5,000 per month. He tendered his resignation and his last day of service is on the 16th of August.
Using method 1:
From 1 - 16 August, there are 14 working days excluding Sundays.
Daily rate: RM 5,000 / 26 = RM 192.31
Prorated salary: RM 192.31 x 14 = RM 2,692.34
Using method 2:
Daily rate: RM 5,000 / 31 = RM 161.29
Prorated salary: RM 161.29 x 16 = RM 2,580.65
Using method 3:
From 1 - 16 August, there are a total of 12 working days.
Total working days in August: 22
Daily rate: RM 5,000 / 22 = RM 227.27
Prorated salary: RM 227.27 x 12 = RM 2,727.27
Conclusion
Method 1: RM 2,692.34
Method 2: RM 2,580.65
Method 3: RM 2,727.27
Safest way of calculation is Method 1.