Dechreuodd y sefydliad gasglu a rheoli dwy dreth ddatganoledig Cymru ar 1 Ebrill 2018. O ganlyniad i gyflwyno'r trethi, y dreth trafodiadau tir a'r dreth gwarediadau tirlenwi, cafodd Cymru’r trethi cyntaf yn benodol i Gymru ers bron i 800 mlynedd.
The WRA started collecting and managing two devolved Welsh taxes on 1 April 2018. The introduction of the taxes, land transaction tax and landfill disposals tax, resulted in Wales gaining the first specifically Welsh taxes in almost 800 years.