IHTM33121 | Loss on sale of land: changes in the interest or underlying land: general
From HM Revenue & Customs · Inheritance Tax Manual
You will need to adjust the sale price where some changes take place in either
the interest, or
the underlying land
at some time between the date of death and the date of sale (IHTM33071), IHTA84/S193.
IHTA84/S193 also contains provisions to take account of possible statutory compensation (IHTM33130).