How Do I Calculate Salary and Overtime for a Marketing Trip to Mumbai?

This month, our company's marketing person was on company work in Mumbai for 4 days. How do I calculate his salary for these 4 days? He is also entitled to overtime.

Questions Regarding Salary Calculation
1. Are there 24 hours in a day?
2. What are the routine working hours?
3. Are 8 hours considered regular working hours, with the remainder as overtime?

Thank you.

I presume the question is like this: You have deputed one of your employees to Mumbai for some work for 4 days. You want to debit the Mumbai office for the services your office has rendered for the Mumbai office, right? Then the cost is the salary of the employee for 4 days, calculated based on his average salary plus the travel expenses, lodging, and boarding admissible. Obviously, if he is paid any overtime payment, that should also be included. Normally, for outstation work, overtime is not paid, but a lump sum amount as bata or daily allowance or outstation allowance is paid.

For marketing employees, every company has its tour and travel policy. Please refer to the company policy for the same because the employee was on duty, and the salary would be provided for only 4 days. For any additional stay, the employee will be entitled to Travel Allowance (TA) and Daily Allowance (DA) as per their respective grade and pay, including their stay in a hotel, food, local conveyance, and miscellaneous expenditure.