Legislation: UK primary law (VAT Act 1994): Section 6(5) 14 day rule for VAT invoices
(5) If, within 14 days after the time applicable under subsection (2) or (3) above, the person making the supply issues a VAT invoice in respect of it, then, unless he has notified the Commissioners in writing that he elects not to avail himself of this subsection, the supply shall (to the extent that it is not treated as taking place at the time mentioned in subsection (4) above) be treated as taking place at the time the invoice is issued.
This rule applies where a VAT invoice is issued within a period of 14 days after the basic tax point. In that case the issue of the invoice creates a tax point which overrides the basic tax point. However, this only applies to the extent that there has not been an earlier tax point under section 6(4) and provided the document that is issued is a VAT invoice as defined in regulation 14 of the VAT Regulations 1995. Individual businesses may, by notifying HMRC in writing, opt to ignore this rule. The basic tax point will then continue to apply even if an invoice is issued within the 14 day period. Similarly the time of supply will revert to the basic tax point where a tax payer, who has not opted out of using the 14 day rule, nevertheless fails to issue a VAT invoice within the 14 days. For further information see VATTOS5235.