Dechreuodd y cynllun gostyngiad ar draean y pris yn 2015, pan benderfynodd Llywodraeth Cymru lansio cynllun peilot i deithio'n rhatach ar fysiau ar gyfer pobl ifanc 16, 17 ac 18 mlwydd oed, ar gyfer unrhyw daith yng Nghymru. Gallai'r estyniad ddigwydd o ddechrau Rhagfyr 2018.
The one-third discounted offer began in 2015 when Welsh Government launched a pilot discounted bus travel scheme to provide all 16, 17 and 18 year-olds with discounted bus fares for any journey within Wales. The extension should take effect from early December 2018.