If the company adjusts the salary without authorization, it will deduct 20% of the salary of the month and pay it at the end of the year. The company's behavior is to deduct wages, and the company should pay wages in full and on time every month. This kind of behavior is illegal.

According to the relevant provisions of the Labor Contract Law:

(1) The company (employing unit) shall pay the workers' wages in full and on time in accordance with the labor contract and state regulations.

(2) If the employer is in arrears or fails to pay the labor remuneration in full, the employee may apply to the local people's court for a payment order according to law, and the people's court shall issue a payment order according to law.

In view of this situation of the company, first negotiate with the company to find a solution. If negotiation fails, you can defend your rights according to law, file a labor inspection or labor arbitration, or directly apply to the people's court for a payment order.