provide the Welsh Government with sufficient relevant and timely information and data to discharge its duties in respect of rate-setting and forecasting for Welsh Income Tax
rhoi digon o wybodaeth a data perthnasol ac amserol i Lywodraeth Cymru er mwyn iddi gyflawni ei dyletswyddau mewn perthynas â phennu cyfraddau a llunio rhagolygon ar gyfer treth incwm Cymru