Get the Irish passport and keep the one you have?
Britain, the Netherlands, Belgium and the Nordic countries treat dual citizenship differently. Here you find out what applies to your family and where you need to look more closely before you apply.
The countries at a glance
The question comes first in every conversation: may I keep my passport. For Britain, Belgium, Sweden, Finland, Denmark and Norway the answer is yes; for the Netherlands it is, as a rule, no. The situations rest on different laws, different dates and have different consequences, and that is why they stand separately on this page.
| Country | Position | Since |
|---|---|---|
| United Kingdom | dual citizenship allowed, nothing to apply for | current law |
| Netherlands | loss by operation of law on voluntary acquisition | Article 15 Netherlands Nationality Act |
| Belgium | no loss on acquiring another nationality | 28 April 2008 |
| Sweden | dual citizenship allowed | 1 July 2001 |
| Finland | multiple citizenship accepted | 1 June 2003 |
| Denmark | dual citizenship allowed | 1 September 2015 |
| Norway | dual citizenship allowed | 1 January 2020 |
The differences are considerable. What holds for Britain does not hold for the Netherlands.
Source: gov.uk, Dual citizenship; Rijkswet op het Nederlanderschap, Articles 15 and 16, on wetten.overheid.nl (text in force since 1 October 2026); Belgian consular service, Losing Belgian nationality; Swedish embassies (swedenabroad.se) on the Citizenship Act of 2001; migri.fi; um.dk, Dual citizenship; udi.no, Dual citizenship. As of: checked 6 November 2026.
The United Kingdom
Dual citizenship is allowed in the UK, and you do not need to apply for it. British law does not treat acquiring another citizenship as a reason to lose British citizenship. There is no permission to keep it and no form to file, because there is nothing to keep that could be lost.
So if you naturalise in Ireland in 2026 or later, you keep your British passport without applying for anything. One practical consequence is worth knowing: while you are in Ireland, the country of your other citizenship, the British government gives you no diplomatic help.
For the next generation the British rules have a fine point of their own. A child born in Ireland to a parent who is British otherwise than by descent, for instance born in Britain, is automatically British by descent. A parent who is British only by descent can, as a rule, not pass British citizenship on automatically to a child born abroad. The details are on the page aboutchildren and the Irish passport. Source: gov.uk, Dual citizenship; Home Office nationality guidance, Children of British parents and Automatic acquisition,checked 6 November 2026.
The Netherlands: loss by operation of law
For Dutch citizens the rule is loss, and it happens automatically. The provision is Article 15 of the Netherlands Nationality Act, the Rijkswet op het Nederlanderschap, here in the wording in force:
Het Nederlanderschap gaat voor een meerderjarige verloren: a. door het vrijwillig verkrijgen van een andere nationaliteit;
An adult loses Dutch nationality by voluntarily acquiring another nationality.
Article 15(1)(a), Rijkswet op het Nederlanderschap, text in force since 1 October 2026
The loss follows directly from acquiring the other nationality, without a decision, without notification and without discretion. Nobody announces it, nobody has to establish it, and a mistake about the consequences changes nothing. Anyone who applies for Irish naturalisation and is granted it loses Dutch nationality at that moment by operation of law, unless one of the exceptions in the next section applies.
The rule is about voluntary acquisition. Acquiring another nationality at birth is not voluntary acquisition and is not a case of loss under Article 15. That is why a Dutch child born in Ireland who is Irish from birth keeps both.
The Netherlands: exceptions, children, life abroad
The law names three exceptions, and for families one of them is the most important line on this page. The loss does not apply to anyone who is married to a citizen of the other country. If you are married to an Irish citizen and naturalise in Ireland, you keep your Dutch nationality. Nor does it apply to anyone born in the other country and living there when they acquire its nationality, or to anyone who lived there for at least five unbroken years before coming of age.
The loss extends to minor children who share in a parent's voluntary acquisition, unless and for as long as the other parent holds Dutch nationality. That is Article 16: if only one parent naturalises and the other stays Dutch, the children keep their Dutch nationality. For a family the order of applications is therefore part of the plan.
A second loss rule hits Dutch dual nationals who live abroad for a long time, and in Ireland it does not run. An adult who also holds another nationality loses Dutch nationality afterthirteen unbroken years of main residence outside the Kingdom and outside the European Union. Ireland is in the European Union, so years in Ireland do not count towards that period.
Clarify before you register
Whether the same consequence follows when Irish citizenship is acquired not through naturalisation but through registration in the Foreign Births Register is not settled. Registration is made on application, and citizenship arises with it. We give no answer to this on a hunch; it needs a written view from a Dutch nationality lawyer on the individual case.
For Dutch citizens that means: clarify first, then register.
Source: Rijkswet op het Nederlanderschap, Articles 15 and 16, wetten.overheid.nl (BWBR0003738), version in force since 1 October 2026, read 6 November 2026.
Belgium and the Nordic countries
Belgium has not taken Belgian nationality from anyone who acquires another one since 28 April 2008, whatever the other nationality. Between 9 June 2007 and that date the loss still applied to the nationality of a short list of states, Ireland among them, so anyone who acquired Irish citizenship in that window lost Belgian nationality at the time. Sweden has allowed dual citizenship since 1 July 2001, Finland has accepted it since 1 June 2003, Denmark since 1 September 2015 and Norway since 1 January 2020. None of these countries treats acquiring Irish citizenship today as a reason for loss.
One thing remains to be done, and it concerns the children. Several of these countries watch their citizens born abroad. In Sweden and Finland a dual national can lose the Nordic citizenship at 22 without a sufficient tie to the country. In Belgium a child born abroad can lose Belgian nationality if no declaration of retention is made between 18 and 28. The details are on the page about children and the Irish passport. Source: Migrationsverket, Losing or retaining Swedish citizenship; migri.fi, Retaining Finnish citizenship at the age of 22; Belgian consular service, Losing Belgian nationality; checked 6 November 2026.
The first step is a conversation
An hour with Sebastian in which your situation is sorted out: your passport, your children's and the order in which you decide.