The effectiveness of this work will be reported at the UK level, as the same standards are being applied to both Welsh and rUK Income Tax liabilities.
Caiff effeithiolrwydd y gwaith hwn ei gofnodi ar lefel y DU, am fod yr un safonau yn cael eu cymhwyso at rwymedigaethau treth incwm Cymru a rhwymedigaethau treth incwm gweddill y DU.