I have personally used these coupons. You can use them on any fare before taxes. The only restriction that I'm aware of is that you can only use ONE $50 certificate per rental, and they do not give "change" if you don't use the whole thing. For example, if your rental total is $45, they will not give you back $5. If your rental is $120, you CAN'T use two $50 certificates to pay for it. You can only use one.