You can book Taj Mahal Tour Guide from the B to B portals like Viator.com, trip Advisor.com. You can also hire their services from travel agencies in Agra. Besides you can book them from U.P tourism Agra office or Department of tourism office from the Mall Road. you can also hire them for Taj Mahal tour guides' office also. https://www.samedaytours.in/taj-mahal-tour-guide.html