Difference between Foregoing Salary and Surrender of Salary
Foregoing of Salary:-
Once salary accrues , its subsequent waiver does not make it exempt from tax liability. Such waiver is treated as only an application of income and hence, it is chargeable to tax.
Example- Mr. Raj is an employee in XYZ Pvt. Ltd. In the month of March 2021, he says to his employer that he is not interested in getting salary for April 2021 and it might be donated to a charitable institution.
Here, the salary for the month of April 2021 will be taxable in the hands of Mr. Raj. However, he is entitled to get deduction under chapter VIA (section 80G of the Income Tax Act, 1961).
Surrender of Salary:-
If an employee surrenders his salary to the Central Government u/s 2 of the Voluntary Surrender of Salaries (Exemption from Taxation) Act, 1961,the salary so surrendered would be exempt.
Difference between advance salary and advance against salary
Advance Salary:- advance salary is taxable on receipt basis.
Advance against Salary:-
it is treated as loan. Loan is different from salary. Advance is generally adjusted with salary over a specified time period. Hence, it is not taxable.