On this page
In brief
- British nationality law defines “parent” in a specific, date-sensitive way.
- The mother is the woman who gives birth; who counts as the father has changed over time.
- A second female parent and the biological-father-versus-legal-parent distinction can matter.
- Who counts as a parent can decide whether nationality passed to a child.
Why “parent” is defined specially
Whether British nationality passed to a child often depends on who the law treats as that child’s parent — and that has not always been the same as the biological relationship. The definition is date-sensitive: different rules apply according to when the child was born. This matters most for unmarried fathers, whose position changed significantly over time.
The mother
For nationality purposes the mother is the woman who gives birth to the child. This has been the consistent position across the frameworks below. (Guide UKF, pp. 7–8.)
The father, across the years
Who counts as the father depends on the applicable framework. In broad terms:
| When the child was born | Who is the father (broadly) |
|---|---|
| Before 1 July 2006 | Ordinarily the man married to the mother; an unmarried biological father was not normally a parent for nationality. |
| From 1 July 2006 | The mother’s husband; a man treated as the father under assisted-reproduction law; or, failing those, a man who satisfies the Home Office as to paternity. |
| From 6 April 2009 | As above, incorporating parenthood under the Human Fertilisation and Embryology Act 2008 (including certain second female parents), with a paternity route where those provisions do not apply. |
These dates are legally central to identifying the framework. (Guide UKF, p. 7; Children guidance, p. 29.) The historic exclusion of unmarried fathers is why the unmarried-British-father and section 4G registration routes exist.
Second female parent
Under the 2008 assisted-reproduction framework, a second female parent can be recognised as a parent for nationality in defined circumstances. This is part of the framework applying from 6 April 2009. (Guide UKF, p. 7.)
Biological father vs legal parent
Being the biological father is not always the same as being a parent for nationality. Proving the biological link (see proving paternity) is one question; whether the applicable law treated that man as a parent when the child was born is a separate one. Both must line up for nationality to have passed.
Later marriage and legitimation
Where the parents married after the birth, the child may have been legitimated under the law connected to the father’s domicile — and, if so, may already be British. Guide UKF warns that automatic citizenship should be checked before registration in these cases. (Guide UKF, pp. 8 and 10.) Domicile and foreign legitimation law are complex and fact-specific.
Why the definition matters
The definition of parent decides whether nationality passed to a child, and which registration framework may need review where it did not — including the unmarried-parent routes, section 4G, and the wider child-registration frameworks.
Our regulatory scope. ENS Immigration Advice is regulated by the Immigration Advice Authority at Level 1 and can help identify which parentage framework may apply in a straightforward case and the evidence areas to review. Disputed parentage, contested domicile, foreign-law legitimation and complex historic nationality fall outside that pathway — we will identify the framework and direct you to the appropriate next step. This page does not resolve who a person’s legal parent is. Refusal or complex issue → specialist referral.
How ENS can help
Identify the parentage rule
We can help work out which date-sensitive parentage framework applied when a child was born.
Evidence areas
We can point to the paternity and parentage evidence a straightforward case tends to rely on.
Escalate a complex issue
Disputed parentage, domicile and legitimation are directed to the right level of help.
Frequently asked questions
Who is a “parent” for British nationality?
British nationality law defines “parent” in a specific, date-sensitive way. The mother is the woman who gives birth. Who counts as the father has changed over time, particularly for unmarried fathers.
Was an unmarried father always a “parent”?
No. Before 1 July 2006, an unmarried biological father was not normally treated as a parent for nationality purposes. Later frameworks changed this for children born on or after that date. (Guide UKF, pp. 7–8; Children guidance, p. 29.)
Who is the father for a child born from 1 July 2006?
From 1 July 2006 the father is generally the mother’s husband, a man treated as the father under assisted-reproduction law, or, where neither applies, a man who satisfies the Home Office as to paternity. (Guide UKF, p. 7.)
What changed from 6 April 2009?
From 6 April 2009 a further framework applies, incorporating parenthood under the Human Fertilisation and Embryology Act 2008, including certain second female parents, with a paternity route where those provisions do not apply. (Guide UKF, p. 7.)
Can there be a second female parent?
Yes. Under the 2008 assisted-reproduction framework, a second female parent can be recognised as a parent for nationality in defined circumstances. (Guide UKF, p. 7.)
Is the biological father always the legal parent?
Not necessarily. Biological paternity and being recognised as a parent for nationality are different questions — the applicable law at the time of birth decides who counts as a parent. See proving paternity.
Does later marriage change things?
It can. Where the parents marry after the birth, the person may be legitimated under the law connected to the father’s domicile and may already be British. (Guide UKF, pp. 8 and 10.)
Why does the definition of parent matter?
It affects whether nationality passed to a child, and which registration framework may apply — including the historic unmarried-father routes and section 4G.
Does this page decide who my legal parent is?
No. It explains the frameworks. Disputed or historic parentage is fact-specific and should be reviewed individually; complex cases are directed to Immigration Help.
How can ENS Immigration Advice help?
ENS Immigration Advice can help identify which parentage framework may apply in a straightforward case. Disputed parentage, domicile and legitimation questions are directed to complex immigration help.
Source basis. Built from Guide UKF (August 2026, pp. 7–8 and 10) and Registration as a British Citizen: Children (version 18.0, p. 29) for the date-sensitive definition of a parent, with links to the detailed registration routes. It does not provide a complete historic analysis of every parentage or legitimation scenario, which can require individual review. Nationality law and Home Office guidance can change; current official guidance should be checked against GOV.UK before relying on the framework.
A question about who counts as a parent?
Identify which parentage framework applied — and whether nationality may have passed — or, where parentage, domicile or legitimation is disputed, get the right level of immigration help.