Updated on: 9 February 2026
At Citizenship.uk, we aim to make the Home Office’s naturalisation rules easier to understand. This guide is for adults (18+) applying to naturalise as a British citizen. It summarises the main requirements and the practical “gotchas” that cause refusals.
While it is not legal advice—it is advisable to discuss your individual circumstances with a specialist lawyer to assess eligibility for British citizenship and the applicable evidential requirements before making an application.
Naturalisation is the route most adults use to become British citizens after living in the UK long-term. It is not an entitlement: even if you meet the legal requirements, the Home Office still makes a decision under the British Nationality Act.
A key point for planning: a citizenship application does not give you immigration status while it is pending. You must keep valid immigration permission until you get a decision and (if approved) complete your citizenship ceremony.
The UK allows dual nationality, but some countries do not. Before you apply, check whether your current nationality allows dual citizenship. GOV.UK explains dual nationality here: GOV.UK: Dual citizenship
If you are eligible under the Windrush Scheme, you normally should not use Form AN. Instead, use the Windrush form on GOV.UK: GOV.UK: Windrush Scheme application form
Even if you apply through Windrush, you may still find parts of this guide helpful for understanding how naturalisation requirements are framed (for example, language/life and good character).
The Home Office policy notes that the Illegal Migration Act 2023 introduced a “citizenship ban” concept for certain people who illegally entered (from 7 March 2023), but that regulations taking effect on 23 July 2024 changed the law so the ban has not taken effect, and applications are considered under the usual law and policy set out in the Form AN guidance.
Important practical warning: even without a separate “ban”, illegal entry can still be a major problem under the good character requirement (see the Good character section below).
Here is the practical checklist we recommend following.
Step 1: Check you meet the requirements (and know what evidence you’ll rely on)
Step 2: Apply and pay the fee
Fees are updated periodically—check the current fees here: GOV.UK: Fees for citizenship applications
Most applicants apply online. Paper Form AN is used in particular scenarios (for example, some applicants living in the Channel Islands, Isle of Man, or a British Overseas Territory, or those applying by post). The form page is here: GOV.UK: Form AN
Step 3: Enrol biometrics when asked
After you submit, you’ll be told how to provide biometrics. Do not ignore the instruction—failing to enrol can invalidate the application.
Step 4: Wait for a decision
The Home Office aims to decide most naturalisation applications within about 6 months, but some can take longer.
Step 5: Attend a citizenship ceremony (if approved)
This is the point you become a British citizen (oath/affirmation + pledge, then you receive your certificate).
Step 6: Deal with “after approval” admin
This includes returning any Home Office-issued immigration document you still hold (where required), and planning travel correctly (passport / right of abode documentation—not your citizenship certificate).
You can apply to naturalise as a British citizen with Form AN only if you are 18 or over. If you are under 18, you normally look at registration instead.
You also usually need to be of “sound mind” (capacity to understand the decision). The Home Office can exercise discretion in some cases.
In plain English, the standard 5-year route normally means you must:
The spouse/civil partner route usually shortens the residence period to 3 years and removes the “12 months after being free from time restrictions” requirement (you still must be free from time restrictions at the date of application). You also do not have the same “future intentions” requirement as section 6(1) applicants.
You should be ready to provide evidence of your spouse/civil partner’s British citizenship and your marriage/civil partnership.
This requirement trips up a lot of applicants.
If you apply under section 6(1), you are expected to have been in the UK exactly 5 years before the Home Office “application date” used for your case.
If you apply under section 6(2), you are expected to have been in the UK exactly 3 years before the relevant application date.
Discretion can exist in genuinely exceptional scenarios. If you applied a little early by mistake, the Home Office may (in some cases) treat a later date as the effective application date, but this can cause delays and may affect fee timing if fees have changed.
Absences are assessed across your whole qualifying period (5 years for section 6(1), 3 years for section 6(2)) and the final 12 months of that period.
How absences are counted: Home Office policy counts whole days and does not count the day you leave the UK or the day you return as “absent” days.
In the final 12 months before applying, the usual expectation is no more than 90 days outside the UK.
If you exceed this, discretion depends on whether you otherwise meet the residence requirements, your ties to the UK, and the reasons for the absences. If total absences exceed 180 days in the final 12 months, discretion is much harder and usually only for exceptional scenarios.
You are expected to have been in the UK lawfully throughout the qualifying period.
In many cases, holding indefinite leave (including settled status under the EU Settlement Scheme) means the Home Office will normally treat you as meeting the lawful residence requirement without needing extensive historical evidence—although there are exceptions and edge cases.
Some Commonwealth nationals have the right of abode. If you have right of abode, you are not subject to immigration control. Overview: GOV.UK: Right of abode
Irish citizens can generally enter and stay in the UK without needing permission (with limited exceptions such as certain exclusion/deportation scenarios). This interacts with the “time restrictions” requirement below.
You must be free from immigration time restrictions at the date you apply.
If you apply under the 5-year route (section 6(1)), you are normally expected to have been free from immigration time restrictions for 12 months before applying.
If you apply under the spouse/civil partner route (section 6(2)), you normally need to be free from immigration time restrictions on the date of application.
Background on eVisas and share codes: GOV.UK: eVisa
If you apply under section 6(1), you must usually intend to make the UK your principal home after you naturalise.
Most applicants must meet both the Life in the UK test and the English language requirement (or Welsh / Scottish Gaelic), unless exempt.
Official booking and guidance are on GOV.UK: GOV.UK: Life in the UK test
For SELT rules and the current approved providers/lists, rely on GOV.UK (updated regularly): GOV.UK: Secure English language tests (SELT)
Good character is a statutory requirement. The Home Office will run checks and expects full, honest disclosure. You should read the official good character guidance before applying: GOV.UK: Good character nationality policy guidance
If you are serving overseas in Crown service (or certain designated services), different residence mechanics can apply. This is a specialised area and you’ll need strong evidence from the relevant employer/authority.
Your application must be endorsed by 2 referees. One must be a professional person; the other must hold a British citizen passport and be either a professional person or over 25, and both must have known you for at least 3 years.
All naturalisation applicants must enrol biometrics as part of identity verification. You are usually asked to complete biometrics within 45 days of submitting the application.
Before applying, make sure you have your identity documents, immigration-status evidence (often via eVisa/share code), and KoLL evidence ready. Always re-check the latest fees just before applying.
Book an online, phone or office consultation, for a small fee, with the UK’s favorite citizenship law firm to determine eligbility for British citizenship and increase your prospects of success.
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