When determining whether the arrangements are tax avoidance arrangements, the tax that would have been payable (or not repayable) if the arrangements had not been entered into is an important factor.
Wrth benderfynu a yw'r trefniadau yn drefniadau osgoi treth, mae'r dreth a fyddai wedi bod yn daladwy (neu na fyddai’n ad-daladwy) pe na bai’r trefniadau wedi cael eu cyflwyno, yn ffactor pwysig.