The return must contain an assessment of the amount of tax chargeable and make a declaration that, to the best of their knowledge the information they have provided is correct and complete.
Rhaid i’r ffurflen dreth gynnwys asesiad o swm y dreth sydd i’w chodi a gwneud datganiad bod yr wybodaeth a ddarparwyd ganddynt yn gywir ac yn gyflawn, hyd eithaf eu gwybodaeth.