Question is not clear, however, i would still try to answer. The tax limit for gratuity is calculated as minimum of the following heads:
1. 15 days' salary, based on the last drawn salary, for each completed year of service
2. Rs. 3,50,000/-; or
3. The gratuity actually received.
Based on this you can probably suggest employees and create your reference.
The minimum period served should not be less than 5 years. You can relax this 5 year period though only as an employee friendly policy and you will not be found in contravention to the law.
Also please follow the minimum gratuity percentage to be kept aside from employee salary and employer's contribution to the same.