The WRA can reject a claim for an amount to be repaid or discharged if repaying or discharging that amount would unjustifiably enrich the taxpayer.
Gall ACC wrthod hawliad am ad-dalu neu ryddhau swm os bydd ad-dalu neu ryddhau’r swm hwnnw’n cyfoethogi'r trethdalwr yn anghyfiawn.