It not only helps more people to pay the right tax at the right time, it reduces the scope for errors and tax avoidance, and enables us to take proportionate action if people make errors.
Os nad awn i'r afael â'r risg dreth hon, gallai arwain at ragor o achosion o bobl yn gwneud hyn yn anghywir ac yn talu’r dreth anghywir.