Section 17 ​​ of the Income-tax Act defines the term ‘salary’. However, not going into the technical definition, generally whatever is received by an employee from an employer in cash, kind or as a facility [perquisite] is considered as salary.

Allowances are fixed periodic amounts, apart from salary, which are paid by an employer for the purpose of meeting some particular requirements of the employee. E.g., Tiffin allowance, transport allowance, uniform allowance, etc. There are generally three types of allowances for the purpose of Income-tax Act - taxable allowances, fully exempted allowances and partially exempted allowances.​

​Yes, these are in the nature of perquisites and should be valued as per the rules prescribed in this behalf.​​

Yes. However, pension received from the United Nations Organisation is exempt.​​

No, it is taxable as income from other sources.​​​