PDFWAC 468-270-130
How can I use the I-405 express toll lanes as a toll-free carpool?
To use the I-405 express toll lanes as a toll-free carpool your vehicle must have:
(1) The required number of occupants as defined in WAC 468-270-120;
(2) A Good To Go!™ toll account in good standing; and
(3) A Good To Go!™ transponder declared in carpool status or other carpool declaration method as defined by the department.