When an enquiry is in progress, any questions arising from the tax return can be referred to an appropriate tribunal for determination, providing that the WRA and the taxpayer agree.
Pan fo ymholiad yn mynd rhagddo, gellir atgyfeirio unrhyw gwestiynau sy’n codi o’r ffurflen dreth at dribiwnlys priodol i benderfynu arnynt, ar yr amod bod ACC a’r trethdalwr yn cytuno.