A Temporary Trip Permit is issued in lieu of IRP plates for travel within Louisiana. The fee for a Temporary Louisiana Trip Permit is $50 and is valid for 48 hours. Permits can be obtained through a permitting service, who will charge an additional processing fee or by mailing application to:Louisiana IRP Processing Center
If you do not hold an IFTA license and will be traveling in Louisiana, purchase enough fuel for the miles traveled in the state and keep receipts in the vehicle.
For more information visit here: https://www.expresslane.org/Pages/faqs/irp_q15.aspx