How British citizenship by descent works
The eligibility rules for British citizenship by descent, in plain English — who may qualify, what disqualifies, and the legal regimes over time, each cited to its primary statute.
Who may qualify
A qualifying path — via the passport direct route
Date keying
- Applies to people born on or after 1983-01-01 (regime selected by birth date, not by when the case is assessed).
Requirements
ALL of the following
the applicant must be the parent of the qualifying ancestor.
- relationship:
- parent
This rule applies to people born on or after 1983-01-01 (it selects a legal regime by the applicant's birth date, not by when the case is assessed).
- birth-date regime boundary:
- 1983-01-01
- comparison:
- born on or after
the qualifying ancestor has a qualifying british otherwise than by descent (confirmed).
- confirmed:
- true
the qualifying ancestor must have held british citizenship at the moment the applicant was born, passing it down the line by descent. Where the claim runs through more than one generation, a later loss of that citizenship is measured against the birth of that ancestor's own child on the line — the point at which it would have passed down — rather than against the applicant's birth.
- required citizenship:
- british
Primary sources
- § British Nationality Act 1981, s.2 — child born abroad to a British citizen otherwise than by descent is British by descent (https://www.legislation.gov.uk/ukpga/1981/61/section/2)
A qualifying path — via the declaration route
Requirements
ALL of the following
the applicant must be the parent of the qualifying ancestor.
- relationship:
- parent
the qualifying ancestor must have held british citizenship at the moment the applicant was born, passing it down the line by descent. Where the claim runs through more than one generation, a later loss of that citizenship is measured against the birth of that ancestor's own child on the line — the point at which it would have passed down — rather than against the applicant's birth.
- required citizenship:
- british
the applicant must have been physically present in united_kingdom for at least 3 years.
- country:
- united_kingdom
- years of presence required:
- 3
the applicant has a qualifying s3 5 both parents uk resident (confirmed).
- confirmed:
- true
the applicant has a qualifying age at application (under 18).
- under 18:
- true
Primary sources
- § British Nationality Act 1981, s.3(5) — registration where the child and both parents have 3 years' ordinary UK residence ending on the application date; confers British citizenship OTHERWISE THAN BY DESCENT (https://www.legislation.gov.uk/ukpga/1981/61/section/3)
A qualifying path — via the declaration route
Requirements
ALL of the following
the applicant must be the parent of the qualifying ancestor.
- relationship:
- parent
the qualifying ancestor must have held british citizenship at the moment the applicant was born, passing it down the line by descent. Where the claim runs through more than one generation, a later loss of that citizenship is measured against the birth of that ancestor's own child on the line — the point at which it would have passed down — rather than against the applicant's birth.
- required citizenship:
- british
the qualifying ancestor must have been physically present in united_kingdom for at least 3 years, with that presence ending before the descendant's birth.
- country:
- united_kingdom
- years of presence required:
- 3
- presence must end before:
- descendant_birth
the applicant has a qualifying s3 2 grandparent otbd (confirmed).
- confirmed:
- true
the applicant has a qualifying age at application (under 18).
- under 18:
- true
Primary sources
- § British Nationality Act 1981, s.3(2) — registration where the British-by-descent parent had a qualifying 3-year UK residence period ending before the child's birth; confers British citizenship BY DESCENT (https://www.legislation.gov.uk/ukpga/1981/61/section/3)
A qualifying path — via the declaration route
Requirements
ALL of the following
the applicant has a qualifying born before 1983 (confirmed).
- confirmed:
- true
the applicant has a qualifying s4c maternal line gender exclusion (confirmed).
- confirmed:
- true
the qualifying ancestor must have held british citizenship at the moment the applicant was born, passing it down the line by descent. Where the claim runs through more than one generation, a later loss of that citizenship is measured against the birth of that ancestor's own child on the line — the point at which it would have passed down — rather than against the applicant's birth.
- required citizenship:
- british
the applicant has a qualifying s4c right of abode counterfactual (confirmed).
- confirmed:
- true
Primary sources
- § British Nationality Act 1981, s.4C (inserted by the Nationality, Immigration and Asylum Act 2002 s.13; ss.4C(3)-(3D) substituted by the Borders, Citizenship and Immigration Act 2009; last amended by the Nationality and Borders Act 2022 s.6(2)) — registration for persons born before 1983-01-01 who would have been British but for pre-1983 maternal-line gender discrimination (https://www.legislation.gov.uk/ukpga/1981/61/section/4C) [GB-01]
A qualifying path — via the declaration route
Date keying
- In force from 2025-07-22 onward — keyed on the assessment date, not on anyone's birth.
Requirements
ALL of the following
the applicant has a qualifying irish citizen (confirmed).
- confirmed:
- true
the applicant must have been physically present in united_kingdom for at least 5 years.
- country:
- united_kingdom
- years of presence required:
- 5
Primary sources
- § British Nationality Act 1981, s.4AA (inserted by the British Nationality (Irish Citizens) Act 2024, commenced 2025-07-22) — simplified registration for Irish citizens with 5 years' UK residence (https://www.legislation.gov.uk/ukpga/2024/19)
Cases that need individual review
Needs individual review
Date keying
- Applies to people born before 1983-01-01 (regime selected by birth date, not by when the case is assessed).
Requirements
ALL of the following
This rule applies to people born before 1983-01-01 (it selects a legal regime by the applicant's birth date, not by when the case is assessed).
- birth-date regime boundary:
- 1983-01-01
- comparison:
- born before
the applicant has a qualifying cukc immediately before 1983 (confirmed).
- confirmed:
- true
the applicant has a qualifying right of abode 31 dec 1982 (confirmed).
- confirmed:
- true
Primary sources
- § British Nationality Act 1981, s.11(1) — a person who immediately before commencement was a Citizen of the UK and Colonies and had the right of abode in the UK became a British citizen at commencement
- § British Nationality Act 1981, s.14(1)(b) — whether that citizenship is held 'by descent', which decides whether it can be transmitted to a child born abroad after commencement (s.14(2) Crown-service carve-out)
- § Immigration Act 1971, s.2 (as enacted, the 31 December 1982 text) — right of abode; s.2(1)(a)/(b)(i) require the relevant acquisition to have been in the UK or the Islands, and s.33(1) confines 'the Islands' to the Channel Islands and the Isle of Man
- § British Nationality Act 1948, s.5(1) and its proviso — CUKC by descent, and the limbs that extend it beyond one generation
Needs individual review
Date keying
- In force from 2022-06-28 onward — keyed on the assessment date, not on anyone's birth.
Requirements
ALL of the following
the applicant has a qualifying s4l historical unfairness claim (confirmed).
- confirmed:
- true
Primary sources
- § British Nationality Act 1981, s.4L (inserted by the Nationality and Borders Act 2022, in force 2022-06-28) — discretionary registration for historical legislative unfairness / public-authority acts or omissions / exceptional circumstances; requires case-by-case Home Office assessment
Needs individual review
Requirements
ALL of the following
the applicant must be the grandparent of the qualifying ancestor.
- relationship:
- grandparent
the applicant has a qualifying commonwealth citizen (confirmed).
- confirmed:
- true
the applicant has a qualifying age at application (meets min 17).
- meets min 17:
- true
the applicant has a qualifying work intention uk (confirmed).
- confirmed:
- true
ANY of the following
The qualifying ancestor must have been born in united kingdom.
- territory:
- united_kingdom
The qualifying ancestor must have been born in ireland pre 1922 between any earlier date and 1922-03-31.
- territory:
- ireland_pre_1922
- window end:
- 1922-03-31
the qualifying ancestor has a qualifying birth location (uk registered vessel).
- uk registered vessel:
- true
Primary sources
- § UK Immigration Rules — UK Ancestry visa (Appendix Ancestry): Commonwealth citizen aged 17+, intending and able to work in the UK, with a grandparent born in the UK / Channel Islands / Isle of Man, OR in what is now Ireland before 1922-03-31, OR on a UK-registered ship or aircraft (https://www.gov.uk/ancestry-visa/eligibility)
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