Cross-border and dual nationality considerations before applying for British citizenship

For internationally mobile individuals, the path to British citizenship involves more than simply counting years of residence in the UK. Cross-border considerations – from the dual nationality laws of your home country to the tax implications of acquiring a second passport and how business travel affects your absence count – can significantly affect both your eligibility and the practical consequences of naturalisation. This post sets out the key issues to consider before making an application.

Does the UK allow dual nationality?

Yes. The UK permits its citizens to hold nationalities from other countries simultaneously with their British citizenship. The Home Office does not require applicants to renounce their existing nationality when they naturalise as a British citizen, and there is no restriction on holding multiple passports under UK law.

As a dual national, you will have the same rights as any other British citizen, including the right to a British passport, the right to vote in UK elections, the right to live and work in the UK indefinitely, and access to public services.

However – and this is the critical point – the UK’s permissive approach to dual nationality does not mean that your other country of citizenship shares that approach. Before applying for British citizenship, you must check the nationality laws of your country of origin carefully.

What does your home country’s law say?

Countries take very different positions on dual nationality, and these vary considerably by jurisdiction:

Countries that do not permit dual nationality at all

In some countries, including China and Malaysia, holding two nationalities is not permitted under national law. If you are a Chinese or Malaysian national and you naturalise as a British citizen, you will be required to relinquish your original nationality. In some cases, this happens automatically upon acquisition of a second nationality.

Countries where you lose your original nationality on naturalisation elsewhere

Nationals of certain countries including India, Japan, and Qatar will lose their original nationality when they acquire British citizenship. The loss is not always immediate or automatic, and the procedural requirements vary, but the result is the same: you will need to decide whether you are willing to give up your existing citizenship before proceeding.

Countries that have recently changed their rules

The landscape on dual nationality is not static. Germany is a significant recent example. Prior to June 2024, German law did not generally allow dual citizenship, meaning that German nationals who wished to naturalise as British citizens faced the difficult choice of renouncing their German citizenship to do so. As of 27 June 2024, Germany now allows multiple citizenships in principle for the first time, a significant change for German nationals living in the UK who had previously decided not to naturalise as a British citizen in order to protect their German nationality. Those who were previously deterred by this restriction may now wish to revisit their options. Austria and the Netherlands have also made changes to their rules in recent years, and the position in other countries continues to evolve.

Countries with conditional or exceptional rules

Some countries permit dual nationality only in specific circumstances or require prior permission before their citizens acquire a second nationality. If you fall into this category, failing to obtain the necessary permission before applying for British citizenship could have serious consequences under your home country’s law.

Countries with no restriction

Many countries, including the United States, Australia, and a large number of European nations, allow dual nationality with the UK without additional requirements.

Given the wide variation, it is essential to seek advice from your country’s embassy or consulate, or a qualified lawyer in your home jurisdiction, before making a British citizenship application.

How can living abroad affect a British citizenship application?

To naturalise as a British citizen under the standard route (section 6(1) of the British Nationality Act 1981), applicants must generally demonstrate five years of continuous lawful residence in the UK. Those married to or in a civil partnership with a British citizen may qualify under a three-year route (section 6(2)). In either case, you must have been physically present in the UK at the start of the qualifying period either five or three years before the date of your application.

Meeting the residence requirement does not mean you cannot travel, but absences must stay within defined limits.

Under the five-year route, applicants must not have been outside the UK for more than:

• 450 days in total during the five-year qualifying period; and
• 90 days in the 12 months immediately preceding the application.

Under the three-year (spouse/civil partner) route, the limits are:

• 270 days in total during the three-year qualifying period; and
• 90 days in the 12 months immediately preceding the application.

It is important to note that meeting the absence limits for ILR does not automatically mean you will satisfy the separate limits for citizenship. The two calculations are distinct, and applicants who qualified for ILR on the spouse route or who spent extended periods abroad during their earlier years in the UK should review their position carefully before assuming they meet the citizenship absence thresholds.

What if my absences exceed the permitted limits?

The Home Office retains a discretion to grant naturalisation even where the absence thresholds have been exceeded, but this is not available in all cases and is not guaranteed.

What cross-border issues can affect internationally mobile individuals?

For individuals whose professional or personal lives span multiple countries, a number of specific issues can arise during the naturalisation process.

Executives, consultants, and others whose roles involve regular international travel need to track their UK absences carefully from the outset of their qualifying period not just in the months approaching an application. A pattern of frequent short trips abroad can cumulatively exceed the permitted threshold even where no single absence appears significant. Keeping a contemporaneous record of travel, including departure and return dates and the purpose of each trip, is strongly advisable.

Where an applicant has been posted or seconded overseas by a UK-based employer, this can affect both the absence count and, in some cases, the qualification for ILR itself. The position will depend on the terms of the posting, whether the applicant maintained their habitual residence in the UK during the absence, and the specific visa route under which they are in the UK. Anyone who has spent a period working abroad during their qualifying period should take advice before applying.

Extended absences to care for family members abroad are common, particularly among individuals with family ties in countries outside the UK. These can be taken into account where the Home Office exercises discretion, but the circumstances need to be documented carefully.

The naturalisation process requires the applicant to demonstrate that the UK is their home. Where an individual splits their time between the UK and one or more other countries, even if they are primarily UK-based, this is likely to be scrutinised. Evidence of settled life in the UK, such as property ownership or rental, employment, schooling for children, and community ties, will all be relevant.

The changing landscape: proposed reforms

The UK’s immigration landscape is currently in a period of significant change. In May 2025, the government published its Immigration White Paper, which proposes to extend the standard qualifying period for settlement (ILR) from five to ten years for most Points Based System migrants and their dependants. Since citizenship applications generally require ILR first, this would, if implemented, substantially extend the overall timeline to British citizenship for many applicants.

The proposals also introduce an “earned settlement” model, under which individuals who make strong economic or social contributions to the UK may be able to qualify for settlement earlier. The detailed criteria for this have yet to be confirmed.

As of the date of this post, these changes have not yet been enacted into law. The qualifying period for ILR and citizenship under current rules remains five years for most routes. However, individuals who are currently eligible or approaching eligibility should be mindful that the rules may change, and that acting sooner rather than later may be advisable if the proposed changes would otherwise apply to their route.

Naturalisation is a significant legal step, and the cross-border considerations outlined above can make it considerably more complex for internationally mobile individuals. Gherson’s immigration team has extensive experience advising on British citizenship applications across a wide range of nationalities, personal circumstances, and immigration routes including cases involving excess absences, complex absence histories, and dual nationality questions.

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The information in this blog is for general information purposes only and does not purport to be comprehensive or to provide legal advice. Whilst every effort is made to ensure the information and law is current as of the date of publication it should be stressed that, due to the passage of time, this does not necessarily reflect the present legal position. Gherson accepts no responsibility for loss which may arise from accessing or reliance on information contained in this blog. For formal advice on the current law please do not hesitate to contact Gherson. Legal advice is only provided pursuant to a written agreement, identified as such, and signed by the client and by or on behalf of Gherson.

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