What is the ruling on the remaining amount from the specified mission expenses, when less than the allocated amount was spent with the knowledge of the employer?

Allah commands the performance of trusts (amanat) and justice in governance. He offered the trust to the heavens, the earth, and the mountains, but they refused to bear it, and man bore it. The Prophet, peace and blessings be upon him, warned against disposing of Allah's money without right, and the righteous predecessors were cautious about public funds. If the mentioned amount is allocated for a specific task and the employee makes an effort to save from it, then the saved amount belongs to him. However, if the employer bears the specified expenses, then any remainder must be returned to them. The ruling on this matter rests with the employer.