Not subject to taxation (6)
I believe the answer is:
exempt
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">not subject to taxation</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for exempt that I've seen before include "Freed from obligation, tax etc" , "Immune - absolve" , "free from tax, say" , "Excused - let off" , "Free (from taxes, etc)" .)