FX Gains and Losses: How UK Businesses Account for Foreign Exchange Under UK GAAP and IFRS

Realised vs Unrealised FX: The Core Distinction#

A realised FX gain or loss occurs when a foreign currency transaction is actually settled — the invoice is paid and the currency is converted. At that point, the sterling amount received (or paid) is compared to the sterling amount at which the transaction was initially recorded, and the difference is a realised gain or loss. An unrealised FX gain or loss occurs when you have an open foreign currency balance at your period-end reporting date — an invoice outstanding, a foreign currency bank account balance — that has moved in value relative to when it was recorded, but has not yet been settled. Unrealised positions must be retranslated at the period-end exchange rate under both UK GAAP (FRS 102) and IFRS.

How FX Differences Flow Through the P&L#

Under FRS 102 (UK GAAP) and IFRS, foreign exchange differences on trading transactions — customer invoices, supplier payables — go through the profit and loss account in the period they arise. This means both realised and unrealised FX differences on trade receivables and payables affect your reported profit. For a business with £500,000 of open USD receivables, a 3% dollar weakening creates a £15,000 unrealised FX loss that flows through the P&L at period end, even though no cash has moved. In the next period, if the dollar recovers, you record a gain. This creates P&L volatility that can obscure underlying trading performance — which is why many businesses try to identify and separately disclose FX gains and losses.

Balance Sheet Treatment and Retranslation#

At each balance sheet date, all foreign currency monetary items — cash balances, trade receivables, trade payables, foreign currency loans — must be retranslated at the closing rate. Non-monetary items (e.g., fixed assets denominated in foreign currency) are generally kept at the historical rate. The retranslation differences on monetary items go to P&L (for most trading items) or to other comprehensive income (for certain designated hedging instruments). Foreign currency bank account balances are a common source of confusion: the unrealised gain or loss on a USD cash balance must be recognised each period even if you have not converted the funds to sterling.

Common SME Accounting Errors in FX#

The most common errors are: (1) Failing to retranslate open foreign currency balances at period end — effectively freezing them at the original transaction rate and missing the unrealised FX movement. (2) Netting realised and unrealised differences into a single "exchange gain/loss" line without distinguishing settled vs open positions. (3) Recording forward contract payments as trading income or expense rather than accounting for the forward as a separate financial instrument. (4) Using the wrong exchange rate — many SMEs use an average rate throughout the month rather than the actual spot rate at the transaction date, which is acceptable as a practical approximation but must be consistent. AskBiz tracks the exchange rate at which each foreign currency transaction was originally recorded and compares it to current rates, flagging unrealised positions that need period-end retranslation.

Hedge Accounting: When It Matters and When It Does Not#

Formal hedge accounting (under IFRS 9 or FRS 102 Section 12) allows businesses to match the accounting treatment of a hedging instrument (e.g., a forward contract) with the hedged item (e.g., a forecast sale), deferring gains and losses on the hedge until the hedged transaction occurs. This reduces P&L volatility from hedging. However, hedge accounting requires formal documentation, ongoing effectiveness testing, and accounting expertise to implement correctly. For most UK SMEs using occasional forward contracts, the administrative burden of formal hedge accounting outweighs the benefit — instead, they record forward contract settlement differences separately and accept the timing mismatch. Discuss with your accountant whether hedge accounting is worth implementing given your transaction volumes.

• Foreign exchange gains and losses are an unavoidable feature of trading internationally, but many SMEs account for them incorrectly — booking everything to an ad hoc "exchange difference" line without distinguishing between realised and unrealised positions, or misclassifying hedging instruments.
• Getting FX accounting right matters for accurate P&L reporting, tax purposes, and bank covenant compliance.