IHTM33036 | Loss on sale of land: procedures: referrals to Technical
From HM Revenue & Customs · Inheritance Tax Manual
Though most claims for relief are straightforward the legislation is complex.
If you have any doubts or difficulties applying the legislation you should refer the problem to Technical. These will include cases where
the claim is made by a person who has not paid or is not paying the tax
the taxpayer wants to withdraw a claim for relief after it has been made
you receive a general enquiry about the operation of the relief.
The relevant instructions will also tell you when you must refer something to Technical.