Dear Hassan,
Basic salary, once fixed, cannot be reduced. However, it is payable based on the number of days worked in a month. All deductions, such as GOSI, as per Saudi Law, will need to be followed.
You are correct that most employment contracts in the UAE/Middle East use a standard 30-day calculation for the payable salary. This simplified model does not include complications of deductibles or contributions towards PF, ESI, etc., which are common in India.
In India, the actual days of each English calendar month are followed to account for statutory deductions, the payment of monthly salary, and compliance with applicable wage laws. However, this practice is not followed in KSA.
Whatever is practiced in KSA is acceptable and compliant with the laws and federal regulations. The calculations are simpler, and charges such as visa fees, IQAMA fees (New/Renewal), etc., are easier to compute.
Rahul
Email: coordial@yahoo.co.in
Phone: 09968270580