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We would like to inform you that if you want to change the employer then you have to get NOC from the old sponsor and cancel the old visa as well. As according to the UAE Labor Law states the blow article in regard of the legal termination:
Article 113 :
An employment contract shall terminate in any of the following cases:
1. By mutual agreement of the Parties, provided that the worker's consent is given in writing;
2. Upon expiry of its term, unless it has been expressly or implicitly extended according to the provisions of this Law;
3. For the convenience of either party to an indefinite term contract, provided that the provisions of this Law concerning the notice and the valid grounds of termination without arbitrariness are adhered to.
Article 117:
1. Either the employer or the worker may terminate an indefinite term contract for a valid reason at any time following its conclusion, by giving the other party a notice in writing at least 30 days prior to termination.
2. For the daily-paid workers, the notice period shall be as follows:
• One week: if the worker has been employed for more than six months but less than one year.
• Two weeks: if the worker has been employed for not less than one year.
One month: if the worker has been employed for not less than five years.
Article 118:
A contract shall subsist throughout the notice period referred to in the preceding Article and shall terminate only on expiry of that period. The worker shall be entitled in respect of the notice period to full pay, calculated on the basis of his last wage, and shall continue to perform his duties during that period if the employer so requests. The Parties may not agree to waive the notice requirement or to reduce the notice period; however, they may agree to extend the period.
Article 119
If either the employer or the worker reduces the period of, or fails to serve a notice of termination on the other, the forbearing party shall pay the other a “compensation in lieu of notice”, irrespective of whether or not the other party has sustained damage as a result of such failure or shorter notice. The said compensation shall be equal to the worker's wage in respect of the entire or reduced period of notice. Compensation in lieu of notice shall be calculated on the basis of the last wage received, in the case of monthly, weekly, daily and hourly paid workers, and on the basis of the average daily wage referred to in Article 57 of this Law in the case of those paid on piecemeal.
Article 80
Before a worker goes on annual leave, his employer shall pay him the full wage due to him plus the leave pay prescribed for him under this Law.
If the company refused to pay allowance of the leave, then you can file a complaint in the labor court.