Is gratuity applicable from the mid of any employment.

Dear Team
My question is that If I joined a company is 2012 & that time they did not have the gratuity benefit & later in 2017 they implemented gratuity in company, in case I leave the company in 2018 & I was entailed in gratuity program from 2017 to 2018 but my total service would be 6 years with company, in this case, will I be eligible to get the gratuity amount or not, If yes then what would be the calculation.
Also, every year our basic salary keep changing and we are getting 4.81% of it as gratuity but at the time of retirement, we will get the gratuity on last drawn basic salary or It will calculate according to the deduction year wise

hi,
You are entitle for gratuity and gratuity will be calculated on the basis of last drawn salary.

your gratuity will be =
(basic salary+ DA if any)* no. of years*15/26

Your query is little bit confusing. You have mentioned that your company has introduced gratuity in 2017. What does it means? There is no necessary to introduce gratuity in company, it is automatically applicable to all industries employing 10 or more employees as per law.
You have further stated that company is paying you all, gratuity @4.81% every year, this is confusing. Could you please elaborate your type of employment, whether contractual, project basis or regular?
Please also confirm before introducing gratuity in 2017 (as per your statement) company has obtained any undertaking and or any type contract as regards to gratuity eligibility. If not, you are eligible for gratuity on last drawn salary (Basic+DA if any) after completion of 5 years continues service.
Regards,
Suresh