Both on-the-job training and on-the-job training within the unit do not belong to the professional and technical training referred to in Article 22 of the Labor Contract Law. Must be trained by a third-party training institution, and issue a training fee invoice from the third-party training institution. Otherwise, the training agreement is invalid.

Assuming that the training agreement itself is legal and valid, the unit has paid the training fee of 30,000 yuan and agreed on a three-year service period, the maximum penalty is 30,000 yuan, which shall not exceed the expenses to be shared during the non-service period. For example, if the service period has been fulfilled for two years, and one year has not been fulfilled, then the employee will have to pay a penalty of 10000 yuan if he leaves early due to resignation. If the service period has been fulfilled for 2.5 years, the penalty is 5,000 yuan.