CFM64360 | Accounts drawn up in a foreign currency: rates used for translation: meaning of 'carried-back amount'
From HM Revenue & Customs · Corporate Finance Manual
The ‘carried-back amount’
CTA10/S17(2) provides a statutory meaning for ‘carried-back amount’. This should encompass all losses that can be carried back for offset against profits of a previous accounting period and that may require translation into sterling when offsetting profits of earlier accounting periods. These are:
Trade losses carried back against total profits - CTA10/S37
Terminal trade losses carried back to an earlier period (but not beginning before 1 April 2017) - CTA10/S45F
Deficits of insurance companies - CTA09/S389(2)
Non-trading deficits from Loan Relationships carried back against profits of any description - CTA09/463B(1)(b) or S459(1)(b))