The Welsh Rates of Income Tax Board (WRIT Board), chaired jointly by the Welsh Government and HMRC oversees the Service Level Agreement (SLA) between Welsh Government and HMRC.
Mae Bwrdd Cyfraddau Treth Incwm Cymru (Bwrdd CTIC), a gadeirir ar y cyd gan Lywodraeth Cymru a CThEM, yn goruchwylio’r Cytundeb Lefel Gwasanaeth (CLG) rhwng Llywodraeth Cymru a CThEM.