What is dual citizenship?

Dual citizenship, also called dual nationality, means being a British citizen and a citizen of at least one other country at the same time. UK law allows it, and you do not need to apply for it. Whether the other country allows it depends on that country's own laws.

How dual citizenship works

Dual citizenship is also called dual nationality. It is allowed in the UK. This means you can be a British citizen and also a citizen of other countries.^{[1]Home Office, Dual citizenship}

You do not need to apply for dual citizenship. If you want citizenship of another country, you can apply for it and keep your British citizenship.^{[1]Home Office, Dual citizenship}

The rules of the other country matter just as much. Many countries do not accept dual citizenship. GOV.UK tells people to check with the consulate or embassy of the country in the UK to find out about its laws on dual nationality.^{[1]Home Office, Dual citizenship}

The Home Office does not hold records of everyone who has British citizenship automatically. Before you travel to the UK, it is your responsibility to check whether you have British citizenship. You may have it automatically if you were born in the UK or have a parent with British citizenship.^{[1]Home Office, Dual citizenship}

Travel, help abroad and your other nationality

Dual nationality changes how you travel and what help you can expect.

There is one exception for people who got British citizenship after settling in the UK under the EU Settlement Scheme. They can travel to the UK on a valid passport of their other nationality, or a national identity card from the EU, Norway, Iceland, Liechtenstein or Switzerland. Before they travel, they need to view their eVisa to check their pre-settled or settled status. They also need to update their UKVI account if their passport or identity card has changed.^{[1]Home Office, Dual citizenship}

Marriage and children

You do not automatically become a British citizen when you marry a person from the UK. You need to apply as the spouse of a British citizen.^{[1]Home Office, Dual citizenship}

In some countries, a married person is automatically counted as having their partner’s nationality. Children may also automatically have a parent’s nationality, even if they were born abroad. The laws of the other country decide this, so GOV.UK again points to its consulate or high commission.^{[1]Home Office, Dual citizenship}

Giving up one nationality

Some people give up British citizenship because the other country does not allow dual citizenship. GOV.UK gives this as an example of why a person might renounce. You can only renounce if you already have another citizenship or nationality, or you are going to get one after giving up your British citizenship. Your right to live in the UK will be affected if you give up citizenship.^{[2]Home Office, Give up (renounce) British citizenship or nationality}

Example

Tomasz was born in Poland and became a British citizen by naturalisation. He still holds his Polish citizenship. The UK does not ask him to give it up.

When he flies to the UK from Canada, he uses his valid UK passport. He does not apply for an ETA, because he cannot get one as a dual citizen. If he has a problem in Poland, the British government cannot give him diplomatic help there, because he is also a Polish citizen.

What people get wrong

People often assume that because the UK allows dual citizenship, every country does. The UK rule only covers British citizenship. Many countries do not accept dual citizenship, so the other country’s law can decide whether you keep your other nationality.

GOV.UK gives this warning on its dual citizenship page.^{[1]Home Office, Dual citizenship}

A second mistake is to travel to the UK on the other passport and assume it works like a visa. Unless you fall into the EU Settlement Scheme exception, you should use a UK or Irish passport or a certificate of entitlement.^{[1]Home Office, Dual citizenship}

The bottom line

The UK allows you to be a British citizen and a citizen of another country at the same time. You do not apply for dual citizenship. The limits come from elsewhere: the other country’s laws, the travel documents you must use to enter the UK and the lack of British diplomatic help in your other country. Check the other country’s rules before you apply for any new citizenship.