When you enter into New Mexico you will come to the port of entry scale house. If you don't have a permit the scale master will automatically tell you to pull around and go inside to get a permit. I paid $43 on a EB weekday and $62 on a WB weekend don't worry about them pulling you in for an inspection they just want your money and you'll be on your way. They take cash,check,tchek or debit card. The Lady's on the west and east port where very friendly.