Guidance

Acquisition of British citizenship: Irish citizens (accessible version)

Published 9 July 2025

Version 1.0

About this guidance

This guidance tells caseworkers about registration as a British citizen for Irish citizens, under section 4AA of the British Nationality Act 1981.

Contacts

If you have any questions about the guidance and your line manager or senior caseworker cannot help you or you think that the guidance has factual errors then email Nationality policy team.

If you notice any formatting errors in this guidance (broken links, spelling mistakes and so on) or have any comments about the layout or navigability of the guidance then you can email the Guidance Review, Atlas and Forms team.

Publication

Below is information on when this version of the guidance was published:

• version 1.0
• published for Home Office staff on 09 July 2025

Changes from last version of this guidance

This is a new piece of guidance.

Acquisition of British citizenship - Irish citizens

Section 4AA of the British Nationality Act 1981 was introduced by the British Nationality (Irish Citizens) Act 2024. It is a registration route for Irish citizens who have been resident in the UK for 5 years.

The law

Under section 4AA of the British Nationality Act 1981, an Irish citizen, of any age, may be registered as a British citizen if:

• they were in the UK at the beginning of a 5 - year period ending with the date of application
• during that period, they were not absent from the UK for more than:
  • 450 days in a 5 - year period, ending with the date of their application
  • 90 days in, the period of 12 months ending with the date of their application
• they were not in the UK in breach of immigration laws at any time in that five - year period
• they are of good character

If, in the special circumstances of a particular case, where a customer does not meet the requirements above the Secretary of State may exercise discretion when considering their application. Guidance on exercising this discretion is set out below.

When referring to absences you must only count whole days’ absences. You must not count the dates of arrival and departure as absences.

For the purpose of section 4AA, residence means physical presence. A customer is to be regarded as present in the UK unless physically absent. A person who is registered under this provision will become a British citizen otherwise than by descent. This means they will be able to pass on citizenship to a child born outside of the UK and overseas territories.

Fees

Fees are payable in accordance with The Immigration and Nationality (Fees) Regulations 2018.

Checking that the customer is an Irish citizen

This route is available to all Irish citizens, irrespective of how they have acquired their Irish nationality. To establish a customer’s Irish nationality, we must see evidence of this in the form of:

• an Irish passport
• an Irish passport card
• Irish certificate of naturalisation
• Irish Foreign Birth Register (FBR) certificate

If a customer claims to be an Irish citizen but does not have one of those documents, you must consider the information provided. However, nationality caseworkers are not expected to have a full understanding of the nationality laws of other countries, and customers are encouraged to produce documentation issued by the Irish government.

Checking an application for automatic claims

You must not grant a certificate of registration to a person who is already a British citizen. If there is nothing in the application to suggest that the customer is already a British citizen, you do not need to investigate this further. Where a customer has an automatic claim to British citizenship you should write to them informing them of the position, explaining that naturalisation is therefore not necessary. You must also arrange for the fee to be refunded.

Section 4AA residence requirements

Those applying for registration as a British citizen under section 4AA of the British Nationality Act 1981 are required to have completed a period of 5 years’ residence in the UK.

To qualify for naturalisation as a British citizen, an individual is required to demonstrate close links with, and a commitment to, the UK. As part of this the expectation is that customers should meet the residence requirements.

Whilst there is some discretion to waive some of these requirements, this cannot be done to the extent that the requirements are ignored.

Check the residence requirements

You must check whether the customer has met the residence requirements by checking Home Office systems.

Customers do not need to submit any documents which have previously been scanned and seen. You must check relevant Home Office systems for evidence of residence.

Whilst customers must be an Irish citizen by the time of their application, they may have had lawful residence in the UK by a form of leave to enter or remain under a different nationality. This lawful residence will still count towards their 5 - year residence period for the purposes of this route.

Passports for Irish citizens will not usually be stamped to show embarkation from the UK. In these and other circumstances, such as where the customer’s passport has been lost or stolen, you must give a customer the benefit of the doubt where claimed absences are within the limits we would normally allow, and there are no grounds to doubt the claim.

Doctors’ letters on their own are not normally acceptable proof of residence. However, if nothing else is available, and the doctors can confirm that they have seen the customer on a regular basis during the period concerned, this may be accepted. If there are gaps in a person’s evidence of residence and it is clear from the information available that they could not have travelled, you may proceed.

Only whole days’ absences should be counted. The dates of departure and arrival should not be counted as absences.

Presence in the UK at the start of the 5 - year qualifying period

We expect customers to have been in the UK on day 1 of the qualifying period as this means they have completed the full 5 years in the UK as required. However, there is discretion to waive this requirement in special circumstances.

To identify the start of the qualifying period, you must use the day after the application date minus the length of the qualifying period. For example, in an application made on 1 August 2025, the customer must have been legally in the UK on 2 August 2020.

Discretion over a customer’s presence in the UK at the start of the qualifying period in exceptional cases

There may be special reasons, such as the customer’s serious ill health, that prevented them from being in the UK at the start of the qualifying period. There is discretion to waive this requirement in special circumstances. Discretion to treat the requirement to have been in the UK on the first day of the residential qualifying period as fulfilled should normally be exercised if one or more of the following apply:

• the customer is normally resident in the UK but there were exceptional reasons why they could not return from abroad at that time such as:
  • illness
  • travel restrictions due to a pandemic
• the customer is a current or former member of the armed forces
• the customer was prevented from being in the UK because they had been removed from the UK, and the decision to remove them was later overturned

If you propose to exercise discretion, you should see appropriate evidence demonstrating why the customer was unable to be present at the start of the qualifying period. For example, if this is based on health grounds, you should see relevant medical evidence.

Cases where the requirement can be met by the date of consideration

Customers are expected to meet this requirement, but there may be cases where the person has inadvertently applied on a date when they did not. The application form will ask customers to agree that the Home Office use a different date as the date of application if this would work to their advantage.

If there has been a fee change between the original application date and the date that they can now meet the requirement (to have been in the UK at the start of the qualifying period), they must pay the fee in force at the time of the new application date.

Changing the application date in this way may be appropriate for applicants who did not meet the requirement to have been in the UK at the start of the qualifying period but meet the requirement by the time you consider their application. When you consider the application, you must assess whether the person would meet this requirement (and the other residence requirements) on either the date you are considering the application, or a date between their original application and consideration. If a person does not meet the requirements on the date of consideration but will do so within the next 2 months, it may be appropriate to put the application on hold. If the person will not meet the requirement for some time, you must consider whether there are exceptional grounds to exercise discretion (please see above for information about discretion).

Absences

You must check the available evidence to see whether a customer meets the residence requirements.

The following can be used as evidence of residence:

• passports or travel documents which have been stamped to show arrival in the UK and entry and departure from other countries: these should be checked against the list of absences that applicants are asked to provide on the application form
• Home Office records and systems
• if the applicant does not have passports to cover the qualifying period - other evidence such as employers letters or tax and National Insurance letters:
  • in such cases you should assess whether there is sufficient evidence to show that that applicant has been resident in the UK during the qualifying period - giving them the benefit of any doubt where claimed absences are within the limits we would normally allow and there are no grounds to doubt the accuracy of the claim

Excess absences in the 5 - year qualifying period

Under section 4AA (3) of the British Nationality Act 1981, there is discretion to waive excess absences in the 5 - year qualifying period.

Where a customer has spent more than the 450 days outside of the UK during the 5 - year qualifying period you must consider exercising discretion if they meet the other requirements.

Where the customer exceeds the permitted absence by 30 days or less you must exercise discretion unless there are other grounds on which the application falls to be refused.

Where the total absences are between 480 to 900 days and the customer otherwise meets the requirements, you must only consider exercising discretion where the customer has established their home, employment, family and finances in the UK, and one or more of the following applies:

• at least 2 years’ residence (without substantial absences, for example: no absences over 90 days within a year) immediately prior to the 5 year qualifying period - if the period to be disregarded is greater than 730 days the period of residence prior to the qualifying period should normally be at least 3 years
• the excess absences were due to postings abroad in Crown service under the government of the UK
• the excess absences were an unavoidable consequence of the nature of a career, for example a merchant seaman or someone in UK based business or employment which requires frequent travel abroad
• exceptionally compelling reasons of an occupational or compassionate nature to justify registration now, such as a firm offer of a job for which British citizenship is a statutory or mandatory requirement
• the excess absences were due to accompanying a British citizen spouse on an overseas appointment
• the excess absences were because the customer was unable to return to the UK because of global pandemic

In other cases, where an applicant’s absences exceed those covered above it is highly unlikely that discretion would be appropriate. You should normally refuse the application and advise them to re-apply when they are able to bring themselves with the statutory requirements, unless there are specific circumstances that warrant exceptional consideration at a senior level.

Excess absences in the final year

When a customer is applying under section 4AA, the following will apply. Total absences:

• of 100 days or less; exercise discretion
• between 100 and 180 days - where the residence requirement across the qualifying period is met – discretion is only appropriate where the customer demonstrates strong links through the presence of family - employment and their home in the UK
• of more than 100 days but not more than 180 days where the residence requirements over the full qualifying period are not met - consider exercising discretion if both the following apply:
  • customers have demonstrated that they have made this country their home by establishing a home, employment family, property and finances in the UK
  • the absence is justified by Crown service or by compelling occupational or compassionate reasons, including inability to travel because of a global pandemic
• exceeding 180 days where the residence requirements over the full qualifying period are met - consider exercising discretion if the customer has demonstrated that they have made the UK their home exceeding 180 days where the residence requirements over the full qualifying period are not met – you must only exercise discretion where the customer has demonstrated that they have made this country their home and there are exceptional circumstances such as Crown Service

Total absences of more than 100 but no more than 180 days where the requirement over the total period is met

You should consider disregarding the absences if the customer has demonstrated links with the UK through the presence here of:

• home
• employment
• family
• finances

You should only disregard if the customer has demonstrated links with the UK and either:

• the excess absences were due to postings abroad in Crown service under the government of the UK
• there are exceptionally compelling reasons of an occupational or compassionate nature to justify registration now, including for example because the customer has a firm offer of a job for which British citizenship is a statutory or mandatory requirement
• the excess absences were because the customer was unable to return to the UK because of global pandemic

Total absences exceeding 180 days where the residence requirements over the total period are not met

You must only disregard in the most exceptional circumstances and where the criteria above are met.

Immigration breaches

Irish citizens can enter and stay in the UK without requiring permission, please see the Common Travel Area guidance. There are some limited exceptions to this, where the person is subject to a deportation order, exclusion decision or exclusion order, or travel ban. They will therefore have been in the UK lawfully during the qualifying period.

Deportation order

If the customer is the subject of an extant deportation order, they will normally fall to be refused.

If it is apparent that the person entered the UK illegally in breach of a deportation order you must refer the person to Immigration Enforcement to consider enforcement action. If Immigration Enforcement are already considering enforcement action and are in contact with the customer, a referral to Immigration Enforcement is not required.

If the deportation order was made before 2 October 2000, on non - criminal grounds on the basis of overstaying or working in breach, you must refer the case to Immigration Enforcement, who will consider whether to revoke the deportation order. If a decision is made to revoke the deportation order you must proceed to consider the application in the usual manner.

Good character

Section 4AA states that, in considering whether to grant an application under this section, the Secretary of State may take into account whether the customer is of good character.

Evidence to be supplied

To guard against the possibility of fraud we should expect to see evidence of identity that satisfactorily satisfies the customer’s eligibility for registration. It should be remembered that a birth certificate is evidence not of identity but of an event.