We refunded around £164,000 to taxpayers because of errors we identified in their tax returns which caused them to overpay tax.
Rydym wedi datblygu ein gallu i ddadansoddi data a chael gwell dealltwriaeth o’r wybodaeth a gawn o’r 60,000 o ffurflenni treth a gyflwynir gan drethdalwyr a'u cynrychiolwyr bob blwyddyn.