Mae Deddf Cymru 2014, a gafodd ei phasio gan y Senedd fis Rhagfyr diwethaf, yn nodi pwerau cyllidol newydd i Gymru, gan gynnwys cymhwysedd deddfwriaethol ynghylch trethu gwarediadau i dirlenwi a thrafodiadau sy’n ymwneud â buddiannau mewn tir.  O Ebrill 2018 caiff trethi presennol y DU yn y meysydd hyn – y Dreth Dirlenwi (LfT) a Threth Dir y Dreth Stamp (SDLT)  - eu disodli yng Nghymru gan y Dreth Gwarediadau Tirlenwi (LDT) a’r Dreth Trafodiadau Tir (LTT).  Y rhain fydd y trethi Cymreig cyntaf ers dros 800 o flynyddoedd, a byddant yn cynnig cyfle i ddatblygu trefniadau ar gyfer trethi Cymreig mewn ffyrdd sy’n adlewyrchu anghenion ein cymunedau a’n busnesau. Ym mis Gorffennaf gosododd Llywodraeth Cymru Fil Casglu a Rheoli Trethi (Cymru) gerbron Cynulliad Cenedlaethol Cymru, cam arwyddocaol o ran hwyluso’r ffordd ar gyfer datganoli trethi .
The Wales Act 2014 passed by Parliament last December set out new fiscal powers for Wales, including legislative competence over taxation of disposals to landfill and transactions involving interests in land. From April 2018 the existing UK takes in these areas – Landfill Tax (LfT) and Stamp Duty Land Tax (SDLT) will be replaced in Wales by Landfill Disposals Tax (LDT) and Land Transaction Tax (LTT). These will be the first Welsh taxes in over 800 years and will provide an opportunity to develop Welsh tax arrangements in ways that reflect the needs of our communities and businesses. In July, the Welsh Government laid before the National Assembly for Wales the Tax Collection and Management (Wales) Bill, marking a significant step in preparing the way for tax devolution .