The below is subject to 1 condition, i.e., you need to get a certificate from an actuary as per AS 15 of ICAI regarding your estimated liability of Gratuity.
Past service liability if funded by payment of single or in installments not exceeding FIVE, then the whole of contribution will be eligible for tax relief in the year of payment
Contribution paid to the trust fund by an employer is treated as an business expenses. (Sec 36 (1)(v))
Under Sec 40 A (7) no deduction shall be allowed in respect of any provision made by the employer for the payment of gratuity to his employees on retirement or termination of their employment. Deduction in computing the income of the assessee for any assessment year is available only on actual contribution of the liability to an approved gratuity fund
The income of an approved gratuity fund is exempt under Section 10(25) (iv)
Conclusion
You can get tax benefit for the amount as much contributed by you towards the fund and actual amount paid during the year as gratuity to your employees.
I hope this is useful to you.
Please consult experts.
Regards,
Rahul