where a change is made by the UK government that has immediate effect and increases amounts of tax raised by a predecessor tax which will have a material effect on the block grant adjustment,
pan wneir newid gan Lywodraeth y DU sy'n cael effaith ar unwaith ac sy'n cynyddu symiau treth a godir gan dreth ragflaenol a fydd yn cael effaith sylweddol ar yr addasiad i'r grant bloc,