if it is in relation to a decision by the WRA to amend a person’s tax return while an enquiry is in progress, the date the person was notified that the enquiry was completed.
os yw mewn perthynas â phenderfyniad gan ACC i ddiwygio ffurflen dreth unigolyn tra bydd ymholiad yn mynd rhagddo, y dyddiad y cafodd yr unigolyn wybod bod yr ymholiad wedi'i gwblhau.