The chargeable consideration exceeds the 0% threshold if it includes any amount on which tax is chargeable at a rate of more than 0% or would be so chargeable were it not for a claim to any relief.
Os yw’r dreth a godir wrth gwblhau’r contract yn uwch na swm y dreth a godir wrth gyflawni'r contract yn sylweddol, rhaid cynnwys y swm ychwanegol yn yr hunanasesiad ar y ffurflen dreth honno.