I bought a Click from a lady in my village who hadn't tax it for 4 or 5 years.
When we went to change the ownership into my wife's name, I paid the outstanding years and taxed it for another incase it was used to go into town, where of course there are police checkpoints.
Many motorcycles aren't taxed here in Isaan, especially if used locally you won't ever be caught going from village to village and around the paddies as we never see a policeman.