Where—
(a)a taxable person (“the recipient”) provides a document to himself which purports to be an invoice in respect of a taxable supply of goods or services to him by another taxable person; and
(b)that document understates the VAT chargeable on the supply,
the Commissioners may, by notice served on the recipient and on the supplier, elect that the amount of VAT understated by the document shall be regarded for all purposes as VAT due from the recipient and not from the supplier.