Is it permissible for an employee to keep the difference in expenses saved from the travel allowance allocated to him, or is that forbidden (haram)? And what must he do if it is forbidden?

The money an employee takes for travel and food expenses falls into two categories:

1. A fixed amount: The money is permissible for him, including any savings from it, even if he did not spend anything. 2. Reimbursement for actual expenses: The true expenses must be declared, and it is not permissible for him to take any excess, as that is considered lying, deception, and a betrayal of trust. This is based on Allah's saying: (O YOU WHO HAVE BELIEVED, FULFILL [ALL] CONTRACTS) (Al-Ma'idah/1), and the Prophet's (peace be upon him) saying: (Muslims are bound by their conditions).

The employee is obligated to abide by the agreement made with his employer.