IHTM33142 | Loss on sale of land: non-qualifying sales: exceptions to the rule for adjusting the price
From HM Revenue & Customs · Inheritance Tax Manual
There is no provision under for taking into account a non-qualifying sale
where the sale price () is less than the value on death (), (where a loss is made) or
where the sale takes place in the fourth year after death () for more than the date of death value.