I have a question regarding prescribed mileage included in box 34 of t4 slip.  This amount is included in box 14 of T4.  As the prescribed mileage rate of .46 per km has rolled into box 14 of T4, can I file a t777auto to reduce the amount received. I will need to receive a T2200 from client / employer, but before I ask the client to get one from his employer, I was hoping to get some feedback if this is even a possible deduction given the circumstances above