IHTM27043 | Foreign property: valuation of assets: fall in value relief on foreign land or buildings
From HM Revenue & Customs · Inheritance Tax Manual
Fall in value relief (IHTM14621) also applies to foreign land. The procedure is the same as for a claim for fall in value relief on UK land - except the value of the sold land must be converted to sterling using the exchange rate as at the date of sale (IHTM14626).