Keeping your original nationality alongside British

The United Kingdom has one of the world's most relaxed approaches to dual citizenship. When you become British, the Home Office does not require you to renounce your original nationality, and British citizens can acquire citizenship elsewhere without losing their UK status. However, whether you can actually keep both passports depends entirely on the rules of your other country—some make you choose.

The UK side: No renunciation required

Under UK law, there is no requirement to give up your original nationality when you naturalise as a British citizen. Similarly, if you are already British and acquire citizenship of another country, the Home Office will not strip you of British citizenship. This applies equally whether you were born British or became British through naturalisation. The British Nationality Act 1981 makes this clear: nothing in the Act forces you to renounce a foreign nationality, nor does acquiring a second passport automatically end your British status.

In practical terms, once you have your British citizenship certificate and passport, you hold dual (or multiple) citizenship unless your other country's laws prevent it. There is no separate application for dual nationality, no extra fee, and no additional process. You simply acquire British citizenship through the standard naturalisation route and retain your existing passport.

The critical question: What does your home country allow?

The crucial piece of the puzzle is whether your country of origin permits you to hold dual nationality. Many countries do not. Some automatically strip your citizenship the moment you acquire another one. Others require you to formally renounce your original nationality before they will let you become British. And a few allow dual status in principle but impose restrictions—like military service obligations or loss of voting rights.

Countries that automatically lose your citizenship upon naturalising abroad include China, India, Japan, and Singapore. Others, such as South Korea, allow dual status up to a certain age (typically 18 or 22) before you must make a choice. Some European nations, including Germany and France, permit dual nationality in some circumstances but not others. The rules are deeply complex and vary by individual circumstances.

When you apply for British citizenship through Form AN (naturalisation), the Home Office will ask you to confirm you understand the requirements. Part of that is explicitly checking whether your country of nationality allows dual citizenship. This is not something the Home Office will investigate for you; it is your responsibility.

Which passport to use when travelling

Once you hold both British and another nationality, you will have two valid passports. The general rule for travel is straightforward in principle but requires careful attention in practice: use the passport of the country you are entering or leaving.

When you travel to the UK, you must use your British passport. This rule became stricter from February 2026 onwards. Dual nationals can no longer simply enter on their non-British passport—even if that passport previously allowed visa-free travel to the UK. You now need to present either a valid British passport, a valid Irish passport, or a certificate of entitlement to the right of abode in a non-British passport. British citizens cannot apply for an ETA (Electronic Travel Authorisation), so if you only hold a non-British passport, airlines and border authorities will not allow you to board or enter.

When you travel to your other country of citizenship, use that country's passport. For example, if you are a dual British-French national travelling to France, present your French passport at French immigration. If you are travelling to a third country where you hold neither citizenship, you can use whichever passport is most convenient—typically the stronger one for visa purposes.

Consular help and the 'master nationality rule'

One important limitation applies to dual nationals: the UK Foreign, Commonwealth and Development Office (FCDO) cannot provide diplomatic or consular assistance while you are physically present in the country of your other nationality.

This is known as the 'master nationality rule'. Under this principle, when you are in a country of which you are a citizen, the UK treats you first and foremost as a citizen of that country. The logic is that your other country should be responsible for protecting you on its own soil. So if you hold both British and French citizenship and encounter trouble in France—a lost passport, a legal dispute, a medical emergency—you cannot call on the British embassy for help. You would need to contact the French authorities instead.

This applies whether or not you are travelling on your British passport. The critical factor is your location, not the document in your pocket. The UK government will make limited informal representations on your behalf in such situations, but formal consular assistance will not be provided.

By contrast, if you are a dual national in a third country where you hold neither citizenship, you can access full UK consular support. A British-French national visiting the United States or Japan, for instance, would be entitled to full assistance from the UK embassy.

Before you apply for British citizenship

If dual nationality is important to you, you must do your homework before you start the naturalisation application. The application fee is non-refundable once the Home Office accepts it as valid, even if it is later refused. For 2026, the naturalisation fee is £1,709, plus a £130 citizenship ceremony fee.

1. Contact your country's embassy or consulate in the UK and ask explicitly whether you will lose citizenship if you become British.
2. If the answer is unclear, consult an immigration lawyer qualified in your home country's law.
3. Ask whether there are any intermediate options—such as applying for permanent residency status, a certificate of citizenship loss, or a special visa category that would preserve some rights.
4. Consider whether you are willing to renounce your original citizenship if that is required. Renouncing UK citizenship is possible but rare; renouncing citizenship of other countries may be harder or involve fees.
5. Document your research. If your home country later claims you never informed them of your naturalisation, written evidence from the embassy or a lawyer's opinion can help.

The Home Office guidance during the application process will remind you to check your home country's rules. This is not a bureaucratic box-ticking exercise—it is a critical step that can affect your legal status for life.

Tax and other obligations

Holding dual nationality can create tax and administrative obligations in both countries. As a British citizen, you are subject to UK tax law regardless of where you live or work. Some countries (such as the United States) tax their citizens on worldwide income even if they live abroad. Others tax only residents. Your dual nationality may affect inheritance, property ownership, and voting rights in both countries.

Before naturalising, consider consulting a tax advisor who has experience with dual nationals to understand what obligations you are taking on. You may owe tax returns, National Insurance contributions, or other compliance costs in both countries.

Summary: The key facts

• The UK never requires you to renounce your original nationality to become British.
• Some countries require you to renounce or automatically strip your citizenship when you become British—you must check first.
• Use your British passport to enter and leave the UK; use your other passport to enter your other country of citizenship.
• You cannot receive UK consular assistance while you are in your other country of nationality.
• Research your home country's rules before applying, as the naturalisation fee is non-refundable if your application is refused.
• Consider tax and legal obligations in both countries before you commit to dual nationality.