VATLP22420 - Option to tax: belated notification of an option to tax: who should process belated notification requests?
If you receive an enquiry from a taxpayer or his agent about a potential belated notification, you must make it clear that the decision on whether to exercise the discretion rests with the National Option to Tax Unit.
All requests for HMRC to accept notification of a decision to opt to tax outside the 30-day time limit must be submitted by the taxpayer, together with the supporting documents, to the National Option to Tax Unit. Their contact details are in paragraph 4.2.3 of Notice 742A.