The rules concerning claims for repayment normally only permit claims to be made within the period of 4 years following the filing date for the return.
Fel rheol, dim ond hawliadau o fewn y cyfnod o bedair blynedd ar ôl dyddiad ffeilio'r ffurflen dreth a ganiateir o dan y rheolau sy'n ymwneud â hawlio ad-daliad.