VAT on carbon tax

Sir, – My gas bill has three elements to it. The daily standing charge. The units I burn. The carbon tax based on the units burned.

These three element are then subtotalled and 13.5 per cent VAT is calculated and added.

Can someone explain to me why am I paying 13.5 per cent VAT on the carbon tax I am being charged, as none of the Ministers I have written to can? – Yours, etc,