Dear Rajaseepmanoj,
It seems you need to understand the basics first - such as what is the salary, what is the gross salary and what is the net salary.
Salary is an earnings which consists of Basic pay and various allowances depending upon the terms of contract or / and status governing the employment.
Gross Salary means total of all earnings.
The term Net salary is a salary in your hand after various deductions from gross towards statutory / non-statutory components.
The salary is calculated on your working days or on your absent days. If you work for less days, your earnings i.e. gross is less and obviously your net.
Overtime is a payment towards your extra work beyond the normal working hours.
Now, you please tell me if I pay you overtime on your net salary, is it acceptable to you?