Rhaid i awdurdodau lleol gwrdd â’r amserlen ar sawl achlysur yn y cyfnod cyn cyhoeddi biliau’r dreth gyngor, gan gynnwys yr angen i fabwysiadu cynllun Gostyngiadau’r Dreth Gyngor erbyn 31 Ionawr. Mae’n hanfodol, felly, fod y diwygiadau yn cael eu gwneud cyn gynted â phosibl. Os nad oes modd llunio’r rheoliadau diwygiedig mewn pryd, gallai awdurdodau orfod wynebu costau sylweddol iawn ar gyfer ailgyflwyno biliau’r dreth gyngor.
Local authorities are subject to a range of deadlines in the run up to issuing council tax bills, including the need to adopt a Council Tax Reduction scheme by 31 January so it is vital that the amendments are made as soon as possible.  If it is not possible to make the amended regulations in time, authorities may incur very substantial costs for council tax rebilling.