Aslamo alikum I do work in free zone used Cars ...

If the employer refuses to pay you your gratuity, you can file a complaint at  the Ministry of Human Resources and Emiratisation against the employer. Your complaint will be referred to the Labor Court, as it does not discuss complaints related to companies operating in the free zones.
Moreover, the end of service benefits are calculated at the rate of twenty-one days' salary for each year of service, as these are calculated on the last basic wage after excluding all allowances.
The UAE labor law, related to your inquiry: 

Article 132
A worker who has completed one or more years of continuous service shall be entitled to severance pay at the end of his employment. The days of absence from work without pay shall not be included in calculating the period of service. The severance pay shall be calculated as follows:
1. 21 days' wage for each of the first five years of service.
2. 30 days’ wage for each additional year of service provided always that the aggregate amount of severance pay should not exceed two year's wage.
Article 133
A worker shall be entitled to severance pay for any fraction of a year he actually served, provided that he has completed one year of continuous service.
Article 134
Without prejudice to the provisions of laws that grant pensions or retirement benefits to employees in certain firms, severance pay shall be calculated on the basis of the wage last due for monthly, weekly and daily paid workers, and on the basis of the average daily wage referred to in Article 57 hereof for those paid on piecemeal. The wage used as a basis for calculating severance pay shall not include whatever is given to the worker in kind, housing allowance, transport allowance, travel allowance, overtime pay, representation allowance, cashier’s allowances, children education

 

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