What is the religious ruling regarding an employee who signs in for attendance at his government job, then leaves for another job?

This act is Islamically forbidden, as it involves lying and deception, and the money acquired from it is unlawful; as Allah Almighty says: "And do not consume your properties among yourselves through falsehood." The perpetrator must offer sincere repentance and return the money to the governmental employing entity or seek their forgiveness for it. The fact that the entity is governmental does not make deception permissible.