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HMRC internal manual

Capital Gains Manual

Debt on security: exchange gains

If a debt is denominated in a foreign currency, exchange gains (or losses) can arise if the currency fluctuates against the pound. You should consider whether any such debt is the debt on a security purely in terms of the currency in which the debt is denominated. Neither realised, nor potential, exchange gains or losses should be taken into account in deciding whether a debt is the debt on a security.