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The short answer
UK foreign tax credit relief is given for foreign tax actually paid, up to the UK tax on the same income or gain, so you cannot claim credit for Nigerian tax that has not yet been assessed or paid. File your UK return on time and pay the UK tax, then amend the return once the Nigerian tax is paid and evidenced; HMRC's guidance allows an online amendment within 12 months of the filing deadline, with other routes after that.
Timing rarely lines up between the two systems. You sell land in Ogun State in August, the UK return for that tax year is due the following January, and the Nigerian assessment arrives months later, or not at all until someone chases it. The temptation is to enter an estimate of the Nigerian tax on the UK return and move on. HMRC's rules point the other way.
What HMRC credits
HMRC's helpsheet HS263 (2026) describes the credit as the lower of the foreign tax paid, or the amount the treaty allows, and the UK tax on the same income. Tax above the treaty rate is not creditable, and HS263 says the person may be able to recover it from the foreign tax authority. The SA106 notes ask for the foreign tax in its own column and an X where you claim the credit.
The word that matters is 'paid'. An estimate, a quote from a Nigerian consultant or an unpaid assessment is not foreign tax paid. Tax withheld at source is different: if a tenant or a bank deducted it and gave you a receipt, you have evidence of tax taken. See when a tenant deducts WHT from rent.
The practical sequence
- Report the income or gain on your UK return in full, by the deadline.
- Claim credit only for Nigerian tax already paid and evidenced.
- Pay the UK tax due.
- Pursue the Nigerian assessment and pay it; get an official receipt.
- Amend the UK return to add the credit, and HMRC will repay or reduce the UK tax.
On amendments, the HMRC campaign letter of October 2026 published by ICAEW says returns can be amended in the online tax account within 12 months of the Self Assessment filing deadline. If the Nigerian tax is paid after that window closes, a later claim may still be possible, but the time limits were not on the official pages we opened, so ask HMRC or an adviser before the window ends.
Gains on Nigerian land: which route to report
GOV.UK says the real-time Capital Gains Tax service cannot be used to claim foreign tax credit relief on overseas property. If you sell Nigerian land, report on Self Assessment, where the credit can be claimed and later amended. The computation itself is set out in working out a Nigerian land gain in pounds.
Worked example (illustrative)
| Step | Amount |
|---|---|
| UK tax on the sterling gain from a Nigerian plot | £1,800 |
| Nigerian tax paid by the UK filing deadline | £0 |
| UK tax paid with the return | £1,800 |
| Nigerian tax later assessed and paid, converted | £1,500 |
| Credit claimed by amendment (lower of £1,500 and £1,800) | £1,500 |
| UK repayment due after amendment | £1,500 |
| Final UK tax | £300 |
Example: if the Nigerian tax had been £2,100 instead, the credit would be capped at £1,800, the UK tax would fall to nil, and the extra £300 would not be refunded by HMRC. For both countries' tax on a sale, see tax on a property sale in both countries and Nigerian CGT for a UK resident.
Converting the Nigerian tax
The SA106 notes say foreign income is converted at the exchange rate when it arose. They do not set a separate rule for converting foreign tax paid later, and we did not find one on the pages we opened. Use a reasonable rate, record the source and date, and apply the same method each time; ask HMRC if the amount is large.
Evidence that counts as Nigerian tax paid
- An official receipt or payment confirmation from the Nigerian tax authority in your name, identifying the year and the income or asset.
- A withholding tax receipt or credit note from the payer, showing your tax ID, the gross amount and the tax deducted.
- The assessment notice that the payment relates to, so HMRC can see the tax and the income match.
- Your conversion workings, with the rate and its source.
If the Nigerian tax is later reduced or refunded after you have claimed credit for it, the credit you claimed would then be too high. Tell HMRC and amend the return, rather than leaving the overclaim in place.
What not to do
- Do not leave the income or gain off the UK return because the Nigerian side is unsettled.
- Do not claim an estimated credit and hope to correct it later; a claim must reflect tax paid.
- Do not rely on a payment receipt that is not in your name or does not identify the income or asset.
- Do not let the 12-month amendment window pass without either amending or asking HMRC about a later claim.
For how the UK-Nigeria treaty allocates taxing rights, read foreign tax credit relief under the treaty.
Questions people ask
Can I claim foreign tax credit for Nigerian tax I haven't paid yet?
No. HMRC gives credit for foreign tax paid. File and pay the UK tax, then amend once the Nigerian tax is paid.
How long do I have to amend my return to add the credit?
HMRC guidance allows amendment in the online account within 12 months of the filing deadline. Ask HMRC about later claims before that window closes.
Can I use the real-time CGT service for a Nigerian land sale?
GOV.UK says it cannot be used to claim foreign tax credit relief on overseas property, so use Self Assessment.
What if the Nigerian tax is more than the UK tax?
The credit is capped at the UK tax on the same gain or income. HMRC does not refund the excess.
Sources
- HMRC HS263: Relief for foreign tax paid (2026) · accessed Oct 2026
- HMRC: SA106 Foreign notes 2026 · accessed Oct 2026
- ICAEW: HMRC one-to-many campaign letter on offshore funds (Oct 2026) · accessed Oct 2026
- GOV.UK: Report and pay Capital Gains Tax, other capital gains · accessed Oct 2026
This article is general information, not financial, legal or tax advice. Products described are provided under the terms on this site and are subject to regulation and eligibility.