Mae Deddf Cymru 2014 yn rhoi’r pwerau i Lywodraeth Cymru i gyflwyno cynigion ar gyfer datblygu trethi newydd mewn meysydd lle mae’r cyfrifoldeb wedi’i ddatganoli. Byddai’n rhaid i’r cynigion hyn gael eu cymeradwyo gan y Cynulliad Cenedlaethol, gan Lywodraeth y Deyrnas Unedig a chan Dŷ’r Cyffredin a Thŷ’r Arglwyddi.
The Wales Act 2014 provides the Welsh Government with powers to put forward proposals for the development of new taxes in areas of devolved responsibility. These proposals must be agreed by the National Assembly, UK Government and both the House of Commons and the House of Lords.