WAC 132D-116-100
WAC 132D-116-100. Display of permit
(1) A permanent permit shall be displayed affixed to the inside of the rear window on the lower left corner directly behind the driver. If the vehicle is a convertible or has no rear window, the permit shall be affixed to the top center of the windshield.
(2) Permits for motorcycles shall be affixed in visible locations.
(3) A special or temporary parking permit shall be placed within the vehicle where it can be plainly observed.