9(1)A person discloses an inaccuracy or a failure to disclose an under-assessment by—
(a)telling HMRC about it,
(b)giving HMRC reasonable help in quantifying the inaccuracy or under-assessment, and
(c)allowing HMRC access to records for the purpose of ensuring that the inaccuracy or under-assessment is fully corrected.
(2)Disclosure—
(a)is “unprompted” if made at a time when the person making it has no reason to believe that HMRC have discovered or are about to discover the inaccuracy or under-assessment, and
(b)otherwise, is “prompted”.
(3)In relation to disclosure “quality” includes timing, nature and extent.