I work for state government, and my employees are responsible for auditing employee travel expenses. I hear this argument once in a while. Our travel regulations clearly state that we will only reimburse up to 15% on meals. That being said, employees are free to leave tips bigger than 15% they just won't be reimbursed for it. I think if people are so concerned about the size of the tip on expensed meals they should not have a problem with it coming out of their own pocket.