Over the last six months we have been working with retailers and the British Retail Consortium (BRC) to gather data from a sample of retailers to establish an estimate of the impact of the charge.
Dros y chwe mis diwethaf, rydym wedi bod yn gweithio gyda manwerthwyr a Chonsortiwm Manwerthu Prydain (BRC) i gasglu data oddi wrth sampl o fanwerthwyr i amcangyfrif maint effaith y tâl.