Is it permissible to keep the money given by the company for food, drink, and transportation during travel and use it for personal purposes instead of the taxes deducted from the salary, while submitting a fabricated report upon return?

If the money paid to an employee as travel allowance is for the employee to spend as they wish, then there is no harm. However, if the money is designated to be spent on specific things, then the employee is not permitted to spend it except on what the company has specified. Nor is the employee allowed to submit a false report, because that constitutes consuming people's wealth unlawfully. Allah has forbidden this, saying: "And do not consume one another's wealth unjustly" (Al-Baqarah: 188). And Allah the Almighty said: "O you who have believed, fulfill [all] contracts" (Al-Ma'idah: 1).