Case 3/Case C will result in a refusal to make the refund if the taxpayer has delayed making their claim when they had time to make an amendment to their return.
Bydd Achos 3/Achos C yn arwain at wrthod rhoi ad-daliad os yw’r trethdalwr wedi oedi cyn gwneud yr hawliad pan oedd ganddo amser i ddiwygio ei ffurflen