Local authorities (in respect of the local rating lists) and the Welsh Government (in respect of the central rating list) are responsible for NDR billing and the application of reliefs.
Awdurdodau Lleol (mewn perthynas â'r rhestr ardrethu leol) a Llywodraeth Cymru (mewn perthynas â'r rhestr ardrethu ganolog) sy'n gyfrifol am anfon biliau ardrethi annomestig a chymhwyso rhyddhadau.