Provision for gratuity is generally not allowable as a deduction except in the following cases :-

Payment towards an approved gratuity fund - Subject to Sec. 43A
Contribution to unapproved gratuity fund is not allowed as a deduction
Provision for gratuity actually became payable during the relevant previous year

Premium paid for policy taken from LIC for gratuity payments of employees, is allowed u/s 37(1).