Maine is a member of the International Registration Plan (IRP). Maine-registered motor vehicles that travel to another IRP jurisdiction, and which have a gross weight or combined gross weight in excess of 26,000 pounds or three or more axles on the power unit, must be registered in the IRP. Qualified motor vehicles from another IRP jurisdiction must have Maine on the cab card or have a valid Maine IRP trip permit prior to entering Maine. Vehicles from non-IRP jurisdictions may operate into or through Maine in interstate commerce only. Non-apportioned vehicles operating intrastate must register in Maine or obtain trip permits. Motor vehicles are registered on the basis of combined gross weight - total weight of the vehicle and maximum load to be carried. For combination vehicles, the gross weight is on the power unit. A motor vehicle may not be operated in excess of the maximum weight allowed for its configuration without additional permits.
72 -hour IRP Trip Permit ($25.00 + $3.00 Fax Fee)
In lieu of fuel tax licensing you may obtain trip permits. Maine's 72 Consecutive Hour Fuel Trip Permit may be obtained through a permit service or directly through the Fuel Unit by calling (207) 624-9000 ext. 52137. The fee is fifty dollars ($50) for 72 consecutive hours.
IFTA Fuel Trip Permit ($50.00 + $3.00 Fax Fee)
Combination IRP/IFTA Trip Permit ($75.00 + $3.00 Fax Fee)
Source of information: https://www.maine.gov/sos/bmv/commercial/irp.html