In accordance to the Employment Act, your employer must pay your prorated salary at least once a month and within 7 days after the end of the salary period. There are exceptions for overtime, resignation without notice and other situations.
When an employee joins a company or ceases employment during a month, thereby having an incomplete month of service, the prorated salary payment may have to be apportioned accordingly. The monthly prorated salary employee is based on the number of days in the respective month. The apportionment is made on a calendar month bases because the salary payment is contracted on a monthly basis, whether the month has only 28 days as in February or 31 days as in August the employee gets the agreed monthly salary.