TAXI REGULATION (SMALL PUBLIC SERVICE VEHICLE)
REGULATIONS 2015.
PART 7
OPERATING REQUIREMENTS.
Prohibition on advertising.
48. (2) The holder of a small public service vehicle licence shall not permit the use of any electronic advertising sign in or on the vehicle associated with the licence such that it is visible from the exterior of the vehicle unless such sign has been approved in writing by the Authority.
(5) The holder of a taxi licence shall not display, or permit the display of, any sign or advertisement on the side doors (other than the front doors) of the vehicle associated with the licence—(a) where the sign or advertisement is greater than 1,600 square centi-metres in area,
(7) The holder of a small public service vehicle licence shall not display, or permit the display of, on the exterior of the vehicle, or on the interior such that it is visible from the exterior of the vehicle, signs providing names, details or logos of industry representative groups.
https://www.nationaltransport.ie/wp-content/uploads/2011/12/Taxi_Regulation_Small_Public_Service_Vehicle_Regulations_2015_-_S_I_No_33_of_2015.pdf