Collecting passports is a legitimate hobby. But every nationality law has an opinion about your other nationalities, and some of those opinions are expensive. You can naturalise somewhere, celebrate, and discover a year later that your birth country quietly deleted you on the day you took the oath.
This guide covers the rules as of September 2026. For the routes to a second passport, see second passports, citizenship by descent and fastest naturalisation.
Two questions, always#
- Does the new country let you keep your old nationality? Some require you to renounce it before or after naturalisation.
- Does your old country let you keep its nationality? Some take it away automatically when you voluntarily acquire another.
A “yes” to one question tells you nothing about the other. Austria happily naturalises people from countries that allow dual citizenship – but still requires them to give up their old passport.
The comparison table (as of September 2026)#
| Country | Naturalising there: keep your old passport? | Its citizens naturalising abroad: keep this one? | Worth knowing |
|---|---|---|---|
| Germany | Yes, since 27 June 2024 | Yes, since 27 June 2024 | German passport law requires Germans to use a German passport or ID to enter and leave Germany |
| Austria | Generally no – renounce | No: automatic loss, unless a retention permit (Beibehaltungsbewilligung) was granted beforehand | Exceptions, e.g. for descendants of victims of Nazi persecution |
| Switzerland | Yes | Yes | – |
| Netherlands | In principle no; exceptions (e.g. married to a Dutch citizen, born and living in the Netherlands, refugees) | Automatic loss, unless you were born and live in the other country, lived there 5 years before 18, or are married to one of its nationals | Dual nationals living outside the EU for 13 years lose Dutch citizenship unless they renew their passport or ID |
| Spain | Only nationals of Ibero-American countries, Andorra, Philippines, Equatorial Guinea, Portugal and France | Spaniards living abroad lose it unless they declare within 3 years that they want to keep it – no loss for the countries listed | Agreement with France in force since 1 April 2022 |
| Italy, France, Portugal, Greece, Cyprus, Malta | Yes | Yes | – |
| Ireland, UK | Yes | Yes | – |
| Poland | Yes | Yes | Poland treats you only as a Pole on its territory |
| Norway, Denmark, Czechia | Yes (Norway since 2020) | Yes | – |
| Slovakia | Check with the interior ministry | Kept only if you lived in the other country for 5+ years (since April 2022); report within 90 days | – |
| United States | Yes (the oath includes renunciation wording, but the US doesn’t enforce it on other countries) | Yes | US citizens must enter and leave the US on a US passport – and stay US taxpayers |
| Brazil | Yes | Yes, since Constitutional Amendment 131 (October 2023) | Loss now only on express request |
| Mexico | Formal renunciation required | Mexicans by birth can’t lose Mexican nationality | – |
| Türkiye | Yes | Yes, but tell the Turkish authorities | Military service rules apply to men |
| Japan | Renunciation required | No: automatic loss on voluntary acquisition | Dual nationals from birth must choose before 20 (since April 2022) |
| South Korea | Limited: some groups may keep it with a pledge not to exercise the foreign nationality | Loss on voluntary acquisition | Men face military-service limits on renouncing |
| India | Renunciation required | No: automatic loss (Citizenship Act, section 9) | Overseas Citizenship of India (OCI) is a lifelong visa, not citizenship |
| Singapore | Renunciation required | No | Dual nationals from birth must renounce the foreign one by 22 |
| China | Renunciation required | No: automatic loss for nationals settled abroad | China doesn’t recognise dual nationality |
| UAE | By nomination only | Generally no | – |
| Andorra | Renunciation required (plus 20 years of residence) | No | – |
The table covers adults acquiring a nationality voluntarily. Children born with two nationalities (through parents or place of birth) are treated much more leniently almost everywhere – except where a choice is forced at adulthood, as in Japan and Singapore.
What happens to your first citizenship#
There are four ways a country can react when you naturalise elsewhere:
- Nothing. Germany, Switzerland, Italy, the UK, the US, Ireland, France, Portugal, Brazil and many others simply don’t care.
- Automatic loss. Austria, the Netherlands, Japan, India, China and Singapore end your citizenship by operation of law. No letter, no hearing. You find out at the next passport renewal.
- Loss unless you act. Spain (declare within three years) and Slovakia (5-year residence exception, report within 90 days).
- Keep it with a permit. Austria grants a retention permit in limited cases – but only if it’s issued before you acquire the other nationality. Afterwards, it’s too late.
Germany: the 2024 switch#
The Nationality Act reform of 27 June 2024 ended the old principle of avoiding multiple nationality. Germans no longer lose their citizenship when they naturalise abroad, and they no longer need a retention permit. Foreigners naturalising in Germany can keep their passport, as long as their home country lets them.
The reform isn’t retroactive. Anyone who lost German citizenship before 27 June 2024 has to apply for it again – former Germans living abroad can do so under § 13 StAG.
The side effects nobody mentions#
Tax: your passport usually doesn’t matter – except when it does#
Almost every country taxes by residence. A second passport doesn’t change your tax bill; moving does. See the tax residency guide. The exceptions:
- United States: US citizens are taxed on worldwide income wherever they live and must file every year. Giving up US citizenship can trigger an exit tax for “covered expatriates”.
- Eritrea: levies a 2% diaspora tax on citizens abroad.
- Spain: Spanish nationals who move to a jurisdiction on Spain’s list of non-cooperative territories remain Spanish taxpayers for the year of the move and four more years.
- Germany: the extended limited tax liability (§ 2 AStG) targets people who were tax resident as Germans and move to a low-tax country – for up to ten years, on German-source income.
- Treaties: in the treaty tie-breaker for individuals, nationality is the fourth test after permanent home, centre of vital interests and habitual abode. It rarely decides, but it can.
Military service#
Holding a second nationality can mean a second draft board. Countries with conscription for men include South Korea, Türkiye, Israel and Greece. Türkiye lets citizens living abroad buy out of service for a fee; South Korea restricts men from renouncing Korean nationality until their service obligation is settled.
Germany’s new military service law took effect on 1 January 2026: men born in 2008 or later must fill in a questionnaire, and mandatory screening is planned from July 2027. Service itself stays voluntary for now.
Between countries that signed the European Convention on Nationality (1997), dual nationals generally only do service in the country where they habitually live. Outside that circle, check bilateral agreements.
Consular help#
The classic rule, going back to the 1930 Hague Convention: a country won’t usually protect you against another country whose citizen you also are. If you’re detained in your “other” home country, your embassy may get little or no access – you’re simply a local there.
Practical consequences:
- Enter each country on its own passport. The US and Germany require it by law; many others expect it.
- Keep both passports valid. Losing track of one creates problems at borders, and in the Netherlands it can cost you citizenship.
- EU bonus: as an EU citizen you can ask any other EU state’s embassy for help where your own country has none (Article 20 TFEU).
Public office, jobs and banks#
Some countries bar dual nationals from certain jobs: Australia’s constitution disqualifies them from Parliament, and security clearances often ask about other passports. US citizens also meet banks that refuse them because of FATCA reporting – a second passport doesn’t hide the first one.
Traps and red flags
“Just don’t tell them.”
Automatic loss happens whether your birth country knows about it or not. Using a passport you’re no longer entitled to can lead to fines or worse.
Retention permits after the fact.
Austria’s Beibehaltungsbewilligung must be granted before you acquire the other nationality.
The 13-year rule.
Dutch dual nationals abroad lose Dutch citizenship if they don’t renew their passport or ID within 13 years.
Forgetting the kids.
Children often follow their parents’ loss or can be affected by it. Check family rules separately.
Bought passports and home-country rules.
A citizenship by investment passport triggers automatic loss in the same way as naturalisation.
US citizenship as an accident.
Children born in the US or to US parents inherit lifelong US tax filing.
FAQ#
Can Germans have dual citizenship in 2026?
Yes. Since 27 June 2024 Germans keep their citizenship when they naturalise abroad, and foreigners can keep theirs when naturalising in Germany – if their home country allows it.
Do I lose my Austrian citizenship if I become a citizen elsewhere?
Generally yes, automatically – unless you obtained a retention permit before acquiring the other nationality. Permits are granted only for specific reasons, such as family ties or services to Austria.
Can Indians hold dual citizenship?
No. An Indian citizen who voluntarily acquires another nationality loses Indian citizenship automatically. The Overseas Citizenship of India (OCI) card offers lifelong visa-free entry and many rights, but not voting or a passport.
Which countries don’t allow dual citizenship?
Among the major ones: China, India, Japan, Singapore, the UAE and Andorra, plus – with exceptions – Austria and the Netherlands. Spain allows it only with certain countries.
Does dual citizenship affect my taxes?
Usually not – tax follows residence. The big exception is US citizenship, which brings worldwide US tax filing. Spain and Germany also have nationality-linked rules for people moving to low-tax countries.
Which passport do I use when travelling?
Enter and leave each of your countries on its own passport. For third countries, use the one you applied with or the one with better visa access, and use the same passport for entry and exit.
This guide is general information, not legal or tax advice. Nationality law changes and has exceptions for almost every rule – check the official sources below or book a strategy session to map passports, residence and tax together.
Sources#
- Germany – Nationality Act (StAG)
- Germany – Federal Office of Administration (BVA), citizenship
- Germany – Foreign Tax Act, § 2 AStG
- Germany – Federal Government, questions and answers on the new military service
- Austria – oesterreich.gv.at, loss of citizenship
- Austria – Foreign Ministry, dual citizenship
- Netherlands – NetherlandsWorldwide, loss of Dutch nationality
- Netherlands – IND, dual nationality
- Spain – Ministry of Justice, nationality
- Spain – Civil Code (BOE)
- Japan – Ministry of Justice, choice of nationality
- India – Ministry of Home Affairs, Overseas Citizenship of India
- Singapore – ICA, dual citizenship at 18 and beyond
- China – National Immigration Administration, Nationality Law
- US – Department of State, dual nationality
- IRS – US citizens and resident aliens abroad
- Council of Europe – European Convention on Nationality (ETS 166)
- OECD Model Tax Convention (2017), Article 4
