I don't think I'd want to be caught with a deer that wasn't tagged. Private land deer in Tx don't need to be checked in. However if it was required I would do it. As MO Archer mentioned, not tagging a deer could be construed as poaching. If you don't use the tag on that deer are you planning on using it on another and going over the legal bag limit? Not an accusation mind you just a hypothetical question.