Rhoddodd Deddf Cymru 2014 y pŵer i’r Senedd osod Cyfraddau Treth Incwm Cymru (CTIC). Ar ôl dod i gytundeb y byddai CTIC yn cael eu gweinyddu gan CThEM ar ran Weinidogion Cymru, cafodd y prosiect i weithredu CTIC ei sefydlu o fis Ebrill 2019.
The Wales Act 2014 gave the Senedd the power to set Welsh Rates of Income Tax (WRIT). Following agreement that WRIT would be administered by HMRC on behalf of Welsh Ministers, a project was established to implement WRIT from April 2019.