Mae gan yr awdurdodau lleol bwerau dewisol hefyd i leihau biliau'r dreth gyngor a gallant ddefnyddio'r pwerau hyn i leihau  unrhyw swm ar fil. Mater i bob awdurdod lleol yw a yw'n defnyddio'r pwerau hyn ac mae penderfyniadau'n cael eu gwneud fesul achos. Er tegwch a thryloywder, dylai fod gan yr awdurdodau lleol bolisi clir ynghylch a fydd y pwerau hyn yn cael eu defnyddio, a sut.
Local authorities also have discretionary powers to reduce council tax bills and they can use these powers to reduce a bill by any amount. It is a matter for each local authority whether it uses these powers and determinations are made on a case‑by‑case basis. In the interest of fairness and transparency, local authorities should have a clear policy on whether, and how, these powers will be used.