After the employer and the employee sign the labor contract, if the employer pays the employee to participate in the special skills training, the two sides can re-sign the training agreement, stipulating the service period and liquidated damages, which is legal and effective.

Article 22 of the Labor Contract Law: Where an employer provides special training fees for laborers and provides them with professional and technical training, it may conclude an agreement with the laborers to stipulate the service period.

If the laborer violates the service period agreement, he shall pay liquidated damages to the employer in accordance with the agreement. The amount of liquidated damages shall not exceed the training expenses provided by the employer. The liquidated damages that the employer requires the laborer to pay shall not exceed the training expenses that should be shared for the unfinished part of the service period.

If the employer and the employee agree on the service period, it will not affect the employee's improvement of labor remuneration in accordance with the normal wage adjustment mechanism during the service period.