UK passport and globe

Home / publications / briefings /

Naturalisation as a British Citizen: Concepts and Trends

03 Aug 2018

This briefing gives details about how many foreign nationals acquire British citizenship every year, their demographic characteristics, and the various bases for their grants of British citizenship.

  1. Key Points
    • In 2017, just over 123,000 foreign nationals naturalised as British citizens. This is a decrease on 2016 and brings the number back to similar levels to the early 2000s after a period of significantly higher citizenship grants between 2009 to 2013
    • In 2017, 7% of citizenship applications were refused or withdrawn. The majority of refusals since 2002 have been because of failure to meet either the residence or the ‘good character’ requirements. English language requirements and the Life in the UK test account for a small percentage of rejected naturalisation applications but may deter additional potential applicants
    • In 2017, 56% of naturalisations were of foreign nationals who have lived in the UK for the required five years, plus one additional year as a settled resident. Most of the other 44 per cent is split between spouses and civil partners of British citizens and minor children registering as citizens
    • Amongst those naturalising in 2017 the largest groups in terms of previous citizenship were from India (13% of the 2017 total), Pakistan (8%), Poland (6%), and Nigeria (6%). The share of citizenships granted to EU nationals increased from 12% in 2016 to 26% in 2017
    • Legal barriers, language and integration, and characteristics of the origin country all affect naturalisation rates
  1. Understanding the Evidence

    Naturalisation is the acquisition of British citizenship by someone who held (or continues to hold) foreign citizenship. There are several routes to naturalisation. Adults may qualify for British citizenship through at least five years of residence in the UK, or through marriage to a British citizen (with three years’ residence in the UK as a spouse or civil partner). Naturalising citizens must also meet requirements of ‘good character’, the ability to communicate in English (or Welsh or Scottish Gaelic), and ‘knowledge of life in the UK’ (as assessed by a Life in the UK test, also required for those applying for settlement). Children may qualify for either automatic or discretionary “registration” as British citizens depending on the country of their birth and nationalities of their parents. Home Office administrative data counts citizenship grants of each of these types. Though registrations are not technically naturalisations, at least in Home Office classifications, they are included with naturalisations in this briefing.

    Home Office data includes information on refusals of citizenship applications, including those refused because of a failure to demonstrate language proficiency or knowledge of life in the UK.

    Data prior to 2005 include grants of the “right of abode“ (a form of permission to live permanently in the UK) as a Commonwealth citizen; since 2005, this category, small in number, is recorded separately from naturalisations to British citizenship. Note that all Home Office statistics in this briefing that are greater than 1,000 are rounded to the nearest 100. Figures in tables and charts are not rounded.

Citizenship grants per year more than doubled from 2000 to 2013 but have declined sharply since then

In 2017, just over 123,000 foreign nationals naturalised as British citizens. This is down almost 40% from 2013 when citizenship grants reached almost 208,000, the largest annual number since records began in 1962. It was also lower than the 2016 total of 149,000.

Figure 1

Source: Home Office immigration statistics table cz_01

Residence-related grants increased from 35,000 (43% of all grants) in 2000 to 113,300 (54%) in 2013. There were 68,800 residence-related grants (56% of all grants) in 2017. Naturalisation through marriage almost doubled throughout the 2000s, from 27,400 (33%) in 2000 to 52,600 (26%) in 2009 but then decreased to 18,600 (15%) in 2017. Grants to minor children increased from 19,200 (23%) in 2000 to a peak of 48,700 (25%) in 2010 and stood at 28,600 (23%) in 2017. “Other” categories have fluctuated between 1% and 6%.

Return to top

The number of accepted and rejected citizenship applications is affected by policy and administrative changes

The refusal rate for citizenship has fluctuated over time (Figure 1, above). It increased sharply from 3% in 2013 to 9% in 2015, and stood at 6% in 2017. The Home Office (2018b) attributes the recent decline in the grant rate to the introduction of ‘enhanced checks on cases requiring higher levels of assurance’ in April 2015.

Changes to law and administrative procedures have resulted in notable spikes in naturalisation. For example, 1974-1975 saw an increase in grants to Pakistanis following the Pakistan Act of 1973 (which created a temporary window for Pakistani nationals to register as Citizens of the United Kingdom and Colonies, after which naturalisation would be required as for non-commonwealth nationals). The increase in 1989 followed the opening of a new application processing centre in Liverpool, increasing administrative capacity.

The introduction of the Life in the UK test and more stringent English language requirements in 2004 does not seem to have changed the increasing trend in naturalisations until 2013. It is possible that there would have been more naturalisations without these new requirements and tests (including the fees required to prepare for and take them). The language and knowledge requirements is likely to pose a greater burden on citizens of poorer, less educated and non-English-speaking countries (Ryan 2008), and may have deterred their applications.

Return to top

Residency, marriage, and children are the three main grounds for citizenship grants

British citizenship grants are divided among three main categories: migrants fulfilling the five-year residency requirement, spouses and civil partners of British citizens, and children being registered as citizens. Figure 2 shows about half of grants overall come from residency (56% in 2017). Marriage/civil partnership made up 15% in 2017 and children made up 23%. The remaining 6% were “other” bases for citizenship, including, for example, transfers from British overseas territories citizenship to full citizenship status. The Home Office (2017) notes that the increase in grants on ‘Other grounds’ “was mostly due to increases in decisions under section 1(4) of the British Nationality Act 1981 relating to persons who had spent the first 10 years of their life in the UK, and section 4G (implemented in April 2015), which refers to persons born before 1 July 2006 to a British father, where their parents were unmarried at the time of their birth”.

Figure 2

Source: Home Office immigration statistics table cz_03

Each of the main pathways to naturalisation (residence, marriage, and registration of minor children) grew in numbers from 2000 to 2013, subsequently fell and now seem to be rising in 2016.

Residence-related grants increased from 35,000 (43% of all grants) in 2000 to 113,300 (54%) in 2013, before falling to 60,800 (51%) in 2015 and climbing to 77,600 (52%) in 2016. Naturalisation through marriage almost doubled throughout the 2000s, from 27,400 (33%) in 2000 to 52,600 (26%) in 2009 but then decreased to 26,800 (18%) in 2016. Grants to minor children increased from 19,200 (23%) in 2000 to a peak of 48,700 (25%) in 2010 and stood at 36,900 (25%) in 2016. “Other” categories have fluctuated between 1% and 5%.

Return to top

The share of citizenships granted to EU nationals increased from 12% in 2016 to 26% in 2017

The largest groups of newly naturalised UK citizens in 2017 had prior citizenship from India, Pakistan, Poland, and Nigeria (see Table 1).

Table 1

Top 10 nationalities receiving UK citizenship, 2017

Country of previous nationality 2017
India16,607 13
United States3,1873
South Africa3,1053

Asian and African nationals contributed the most to growth in naturalisations over the 2000s (see Figure 3). Migrants from Asia and the Middle East have seen a decline in the numbers of citizenship grants issued since 2013 and 2012 respectively, but Asia is still the predominant source – with 43,900 grants in 2017.

Following the UK’s 2016 referendum on leaving the EU there was a sharp increase in the number of applications for naturalisation from EU citizens. Nationals of EU countries made up 26% of citizenship grants in 2017, more than double the corresponding share in 2016 (12%). The number of grants to EU nationals increased from 13,000 in 2015 to 31,800 in 2017. In 2016, Poland was the only EU nationality amongst the top 10 countries of previous nationality for those seeking naturalisation, however in 2017 both Italy and Romania also joined the list. Citizens of countries that joined the EU in 2004 accounted for 9% of total grants in 2017 and those that joined in 2007 accounted for 4%; those of pre-existing member states of the EU before 2004 accounted for 13%.

Figure 3

Source: Home office immigration statistics table cz_06

Grants of citizenship to nationals of North and South American countries averaged 21,100 annually between 1983 and 1989 before dropping to 4,900 annually in the 1990s and 10,600 annually from 2000 to 2017.

By age group, adults aged 25-44 comprised the majority of naturalising citizens (54% of the total). Only 15% were 45 and older; 23% were children aged under 16. Women outnumbered men primarily among the 25-34 age group. The proportions are mostly comparable across other age groups.

Return to top

Legal barriers, language and integration, and poverty in origin country affect naturalisation rates

Naturalisation reflects both legal requirements and a personal choice. One would expect that naturalisation is more likely when there are few legal barriers, when naturalisation brings greater benefits, and when naturalising does not entail giving up much of value, such as a previous citizenship.

First, naturalisation rates are lower in nations that impose more legal requirements for acquiring citizenship. Traditionally, nations have been categorized as following one of two logics of citizenship: jus soli (literally ‘right of soil’) where citizenship comes from being born in the country, and jus sanguinis (literally ‘right of blood’) where citizenship comes from parents’ citizenship and in-country birth does not confer citizenship. Contemporary citizenship law in many nations blends the two logics in varying proportions.

Overall, British citizenship law is more open to naturalisation than traditional jus sanguinis nations such as Germany. Although the UK may be viewed as the original jus soli country it is now less open than other traditional jus soli nations such as the USA and Canada.

In a comprehensive comparative study, Janoski (2010) identifies as many as 12 requirements that countries may impose; many of which are now included in British citizenship law (Sawyer 2009). These include requirements of good conduct, language skills, efforts toward cultural integration (measured in the form of the Life in the UK test), years of residency, and navigation of complex and expensive application procedures.

From 2002 to 2017, the majority of refusals to grant citizenship were because of a failure to meet either the ‘good character’ requirement or the residence requirement. The ‘good character’ requirement accounts for an increasing number of rejected applications for naturalisation, rising to 40% of all refusals in 2017 (from 13% immediately before legal changes to this requirement in 2008). Failure to demonstrate language proficiency or knowledge of life in the UK comprised 9% of refusals (720 people), as shown in Table 2. Refusals due to delays in replying to enquiries from UKVI risen in recent years– from 423 in 2013 (6%) to 1,698 in 2017 (17%).

Table 2

Reasons for refusal, naturalisation applications, 2015-2017

Reason for refusal2015%2016%2017%
Total refusals10,64612,5927,714
Incomplete applications2542%1281%521%
Parent not a British citizen7497%9317%3004%
Not of good character4,52442%5,52544%3,11940%
Delay in replying to enquiries from UKVI1,25412%1,69813%1,31917%
Oath not taken in time140%90%10%
Insufficient Knowledge of English and KOL5315%6735%7209%
Source: Home Office immigration statistics table cz_09

British citizenship law also does not require renunciation of prior citizenships in order to naturalise. (Law in the sending nation is relevant here as well. Zimbabwe, for example, has not permitted dual citizenship, probably lowering Zimbabwean naturalisation rates in the UK.)

Research on the determinants of naturalisation and the ways in which costs and benefits to individuals influence their decision to naturalise or not—has been conducted mainly in North America rather than the UK (Bloemraad, 2006). A European study of naturalisation identifies nine factors associated with higher naturalisation rates. For individuals, naturalisation is more likely for migrants who speak the destination country’s language, who have a parent born in the destination country and who have resided longer within it. In addition, people from poor or unstable countries or from former colonies of the destination country are more likely to naturalise. Among the second generation (children of migrants), naturalisation seems to be less common among Muslims than among others. Countries where citizenship law is relatively permissive and where net migration rates are low, the study finds tends to have higher naturalisation rates (Dronkers and Vink 2010).

Return to top

Evidence gaps and limitations

Administrative data on naturalisations provide complete and presumably accurate counts of grants of citizenship by category of eligibility (residence, family, or registration). The Home Office compiles figures from a database in which caseworkers enter information about each applicant for naturalisation. Published statistics are generated from this database.

Since naturalisation represents a change in the relationship between an individual and the government, trends in naturalisation reflect not only trends in migration but also changes in government policy and administrative practice. Several cases are discussed in this briefing in which a change in policy or administrative practice had noticeable effects on the number of naturalising citizens in a given year or period. However, a crucial limitation is that administrative data on applications, grants and refusals cannot show the number of potential citizenship applications that might be deterred by added requirements. These include the 2004 and 2005 changes requiring a higher standard of English language proficiency and a demonstration of knowledge of life in the UK, and the fees accompanying applications for settlement, naturalisation, and the Life in the UK test. Some research attempts to estimate this deterrent effect (Ryan 2008), but this requires estimations based on assumptions and cannot be counted straightforwardly in the data. Still, given that some individuals may not feel capable of passing the required language and knowledge tests, and others may have difficulty affording the fees (particularly families, since fees apply to each individual), this deterrence could be an important impact of these policies.


  • Bloemraad, Irene. “Becoming a Citizen in the United States and Canada: Structured Mobilization and Immigrant Political Incorporation.” Social Forces 85, no. 2 (2006): 667-695.
  • Dronkers, Jaap, and Maarten Vink. “Explaining Immigrant Citizenship Status: First and Second Generation Immigrants in Fifteen European States.” MPRA Paper No. 26198, Maastricht Research School of Economics of Technology and Organization (METEOR), Maastricht University, 2010. Accessed 9 November 2010.
  • Home Office. “British Citizenship Statistics, United Kingdom, 2009.” Statistical Bulletin, Home Office, London, 2010.
  • Home Office. “How many people continue their stay in the UK?.” London: Home Office, 2017.
  • Home Office. “Immigration Statistics, October to December 2017.” London: Home Office, 2018a.
  • Home Office. “User Guide to Home Office Immigration Statistics”, updated May 24, 2018b.
  • Janoski, Thomas. The Ironies of Citizenship: Naturalization and Integration in Industrialized Countries. Cambridge: Cambridge University Press, 2010.
  • Ryan, Bernard. “Integration Requirements: A New Model in Migration Law.” Journal of Immigration Asylum and Nationality Law 22, no. 4 (2008): 303-316.
  • Sawyer, Caroline. “EUDO Citizenship Observatory Country Report: United Kingdom.” Florence: European University Institute, 2009. Accessed 9 November 2010. United%20Kingdom.pdf

Further Reading

  • Brubaker, R. Citizenship and Nationhood in France and Germany. Cambridge, MA: Harvard University Press, 1992.
  • Yang, P. Q. “Explaining Immigrant Naturalization.” International Migration Review 28, no. 3 (1994): 449-477.

Related Materials

Next Update

March 2, 2020


Dr Scott Blinder

Press Contact

If you would like to make a press enquiry, please contact:

Rob McNeil

+ 44 (0)7500 970081

 Contact Us 


This Migration Observatory is kindly supported by the following organisations.

  • University of Oxford logo
  • COMPAS logo
  • Esmee Fairbairn logo
  • Barrow Cadbury logo
  • Paul Hamlyn Foundation logo