Is it possible to change from a non b extension to a non o retirement ext once the non b extension expires? Udate and clarfication: I want to move to Korat after my non b extension expires. I was told to go to Korat immigration 15 or more days and apply by Pathumthani immigration​. I am being told that I have to cancel​ my current extension before I apply which is not posible as I have to finish​ my contract.