Second citizenship: what changes and what doesn't

What this covers

Second citizenship means holding the nationality of two countries at the same time. People usually get it by descent through a parent or grandparent, by naturalization after living in a country, through marriage to a citizen, or in a few countries through investment programs. Each country decides for itself who its citizens are. Germany's Federal Ministry of the Interior says every country determines its own nationals under the general principles of international law, so people may have dual, multiple or no citizenship.

Understand the main routes to a second citizenship

Routes differ by country, but most fall into a few families. The examples come from official pages opened on 8 November 2026. Each has conditions not shown here.

Check whether both countries accept dual citizenship

Two sets of rules apply. The country you are joining may require you to give up your current citizenship. The country you already belong to may take your citizenship away if you acquire another one.

GOV.UK says dual citizenship is allowed in the UK, and also warns that many countries do not accept dual citizenship. It suggests checking with the other country's consulate or embassy. Germany's Federal Ministry of the Interior says that since 27 June 2024 people are naturalized without having to give up other nationalities, and Germans no longer lose German citizenship by acquiring a foreign one.

Rules change. Germany's policy before 2024 was to avoid multiple citizenship. Check the current law of both countries at the time you apply.

Treat investment programs as a category with legal risk

Some countries have offered citizenship in exchange for an investment or payment. These programs change often, and some have been closed or challenged.

In Case C-181/23, the Court of Justice of the EU held on 29 April 2025 that Malta's 2020 investor citizenship scheme amounted to the commercialization of the grant of nationality and, by extension, of EU citizenship. The court's press release says each member state sets its own nationality conditions, but must do so consistently with EU law, and cannot grant its nationality in exchange for predetermined payments or investments.

FlagSage does not list, compare or recommend programs. Check any program with the government that runs it and with a qualified lawyer.

Know that a passport does not move your tax residence

Most countries tax by residence, not citizenship. A new passport does not by itself change where you live, where your home is or where your interests are. Under Article 4(2) of the OECD Model Tax Convention, nationality is only the fourth tie-breaker test, used after permanent home, center of vital interests and habitual abode. See tax residency.

The United States is a major exception. The IRS says US citizens are taxed on worldwide income regardless of where they live. A US citizen who gains a second citizenship stays inside the US system. A person who gains US citizenship becomes subject to it. See United States.

Citizenship can still affect other things, such as the right to live and work in a country and to vote. See citizenship and living base.

Check the duties that come with a second citizenship

Citizenship brings duties as well as rights. Before applying, ask what each country expects of its citizens.

The UK Foreign, Commonwealth and Development Office says that if you are a dual national in the country of your other nationality, it would not normally support you or get involved in your dealings with that country's authorities. It says it cannot help you avoid responsibilities there, such as compulsory military service. In a third country, it can usually give the same support as to other British nationals.

• Compulsory military or national service, and whether it applies to citizens living abroad
• Whether you must enter and leave the country on its own passport
• Tax by citizenship, as in the United States
• Limits on consular help from your other country while you are there
• Rules on passing citizenship to your children and registering births abroad
• Whether either country restricts public office or certain jobs for dual nationals

Know that giving up a citizenship has its own rules

Some people consider renouncing a citizenship, either because a new country requires it or for other reasons. Renunciation is usually a formal legal process run by the country being left, and it can have tax consequences.

For US citizens, the IRS says the expatriation tax rules apply to citizens who renounce. A person can be a covered expatriate based on past tax liability, net worth of $2 million or more, or failing to certify five years of federal tax compliance on Form 8854. Covered expatriates are treated as selling their property at fair market value on the day before expatriation, with an exclusion amount that changes each year. See exit tax.

GOV.UK links to a separate process for giving up British citizenship. Each country sets its own procedure and any fees.

Common misconceptions

Questions to take to a professional

1. Which route to the second citizenship fits my family history, residence or marriage, and what are its current conditions?
2. Does the country I am joining require me to give up my current citizenship?
3. Would my current country take away my citizenship if I acquire another one?
4. What military service, travel document or registration duties would apply to me as a citizen of each country?
5. Would either citizenship bring tax duties based on citizenship rather than residence?
6. How would the second citizenship affect my children's citizenship and my estate planning?
7. If I give up a citizenship later, what are the procedure, the fees and any tax consequences?

Questions people ask

Sources

• Dual citizenship (GOV.UK)Official guidance
• Check if you can become a British citizen (GOV.UK)Official guidance
• Apply for citizenship if your spouse is a British citizen: Eligibility and fees (GOV.UK)Official guidance
• Who the FCDO can support abroadOfficial guidance
• Nationality Law (Federal Ministry of the Interior, Germany)Official guidance
• Registering a foreign birth (Department of Foreign Affairs, Ireland)Official guidance
• Court of Justice of the EU, Press Release No 52/25, Judgment in Case C-181/23 Commission v Malta (Citizenship by investment)Primary law
• Publication 54 (12/2025), Tax Guide for U.S. Citizens and Resident Aliens AbroadOfficial guidance
• Expatriation taxOfficial guidance
• Model Tax Convention on Income and on Capital: Condensed Version 2017 (OECD)Treaty text