Introduction
With a persistently volatile naira and the continuing growth of Nigerian businesses with international customers, foreign currency management has become an everyday challenge for SMEs that previously dealt almost exclusively in naira. But alongside the financial complexity of operating in multiple currencies, there is a tax dimension that many businesses overlook entirely — sometimes until FIRS raises an enquiry.
Whether your business invoices clients in US dollars, holds a domiciliary account, pays for software subscriptions in sterling, or has taken out a loan in a foreign currency, this guide explains the tax rules that apply and the common pitfalls to avoid.
How Foreign Currency Transactions Are Taxed in Nigeria
Under the Companies Income Tax Act (CITA) and the Finance Acts, profits assessable in Nigeria must be computed in naira. This means that all foreign currency transactions — income, expenses, assets, and liabilities — must be translated into naira for tax purposes. The exchange rate used for this translation matters, and using the wrong rate can result in either overpayment or underpayment of tax.
The FIRS requires that transactions be translated at the rate applicable at the date of the transaction — meaning the rate at which the payment was actually made or received, not an average rate for the year. For businesses with high transaction volumes in multiple currencies, this can create significant bookkeeping complexity.
Foreign Exchange Gains — Are They Taxable?
This is one of the most frequently misunderstood areas of Nigerian business taxation. A foreign exchange gain arises when the naira weakens between the time you enter into a foreign currency transaction and the time you settle it. For example:
You invoice a US client for $10,000 when the exchange rate is USD/NGN 1,500 — recognising revenue of NGN 15,000,000. By the time the client pays three months later, the rate has moved to USD/NGN 1,600, meaning you actually receive the equivalent of NGN 16,000,000. The NGN 1,000,000 difference is a foreign exchange gain.
Under Nigerian tax law, unrealised foreign exchange gains — gains that exist on paper because the rate has moved, but where no actual payment has been received or made — are generally not taxable until they are realised. Realised gains, however, are treated as taxable income and must be included in your assessable profits for CIT purposes.
Key distinction: Unrealised vs realised. Many businesses incorrectly include unrealised gains in their taxable income, overpaying tax. Others fail to report realised gains at all, underpaying. Understanding the difference is essential.
Foreign Exchange Losses — Are They Deductible?
The mirror image of the above applies to forex losses. When the naira strengthens, or when you need to buy foreign currency at a less favourable rate than anticipated, you incur a forex loss. Realised forex losses arising from trading transactions (i.e. in the ordinary course of your business) are generally deductible for CIT purposes, provided they are incurred wholly and exclusively for the purposes of the business.
Unrealised losses are typically not deductible until they crystallise — though accounting standards (IFRS or ICAN GAAP) may require them to be recognised in your financial statements. The tax treatment does not always follow the accounting treatment, and reconciling the two requires care.
Domiciliary Accounts and the Tax Treatment of Balances
Many Nigerian businesses hold foreign currency in domiciliary accounts to manage their dollar or sterling income and expenses. The tax treatment of these balances depends on how the funds are used:
- Interest earned on domiciliary account balances is subject to withholding tax and is taxable income for CIT purposes
- Realised gains arising from converting domiciliary account balances to naira at a rate more favourable than the original deposit rate are taxable
- Losses on conversion are potentially deductible if the funds were used for trading purposes
Keeping a clear record of the exchange rate at which foreign currency was received and at which it was ultimately converted is essential — this information is needed to calculate gains and losses correctly and to respond to any FIRS enquiry.
Payments in Foreign Currency to Overseas Suppliers
If your business makes payments in foreign currency to overseas suppliers — for software, consultancy, raw materials, or other services — these payments must be translated to naira at the spot rate on the payment date for inclusion in your accounts. The naira equivalent forms the deductible expense for CIT purposes.
Additionally, as noted in our recent blog on Withholding Tax, payments to non-resident service providers are subject to WHT at 10%, regardless of whether the payment is made in naira or foreign currency. The WHT is calculated on the naira equivalent of the foreign currency payment.
VAT on Foreign Currency Transactions
If your business is VAT-registered and supplies goods or services priced in foreign currency to Nigerian customers, VAT at 7.5% must be charged on the naira equivalent of the supply at the time of the transaction. You cannot invoice in dollars and collect VAT on the dollar amount — the VAT must be computed on the naira value.
For imports of goods, the customs duty and VAT import charges are also computed on the naira equivalent of the customs value — typically based on the CBN official rate at the time of import.
Practical Steps for Managing Forex and Tax
- Record the exchange rate for every foreign currency transaction at the date it occurs — do not rely on end-of-month averages for tax purposes
- Separate your accounting treatment of realised and unrealised gains and losses — they have different tax treatments
- Ensure your accounting software can handle multi-currency transactions and produce a reconciliation of your forex position
- Review your domiciliary account activity for unreported interest income and conversion gains
- Confirm with your accountant whether your current WHT deduction practice covers payments to foreign suppliers
Conclusion
Foreign currency transactions introduce a layer of tax complexity that many Nigerian businesses are not fully prepared for — particularly those that have moved into international markets relatively recently. Getting the exchange rate methodology right, distinguishing realized from unrealized gains, and ensuring WHT is correctly applied on overseas payments are the three areas most likely to attract FIRS scrutiny. Our team works with businesses across sectors to implement proper forex accounting and tax compliance frameworks. If your business is dealing in foreign currency and you are not confident your tax position is correct, contact us for a review.