If you are an adult and wish to make a British citizenship application, there are two key routes available to you. You can apply for citizenship if:
In addition, there are requirements about how long you are allowed to have spent outside the UK during the relevant period.
British Citizenship (Naturalisation) Applications
If you are an adult and wish to make a British citizenship application, you can apply for citizenship if you have been lawfully resident in the UK for at least the last five years and have held indefinite leave to remain/permanent residence for at least the previous 12 months. In addition, there are requirements about how long you are allowed to have spent outside the UK during the relevant period. You must have spent no more than 450 days outside the UK during the past 5 years and no more than 90 days outside the UK in the last 12 months. However, there is discretion which can be exercised in relation to excessive absences should an applicant be able to evidence close links with, and commitment to, the United Kingdom. There is also a good character requirement which has to be met.
British Citizenship (Registration) Applications
For children under 18 wishing to apply for citizenship, there is a different process called ‘registration’. In some circumstances, children can apply to register to become a British citizen if at least one of their parents has become a British citizen or settled in the UK since they were born, or if the child has lived in the UK until they were 10 and has spent no more than 90 days outside the UK in each of the first 10 years of their life, unless there are special reasons for excessive absences.
In some circumstances, an adult can register as a British citizen, subject to very specific criteria, such as you have another form of British nationality, you were born before 1 January 1983 to a British mother or you were born before 1 July 2006 to a British father, even if he was not married to your mother.