Who can aply

British citizenship can be pursued  by foreign nationals who are permanent residents, that is, have been granted Indefinite Leave to Remain (ILR), via naturalisation process.
There are two main paths to applying for naturalisation:
-naturalisation after five years in the UK, or
- naturalisation after three years in the UK (as the spouse of a person settled in the UK).

In either case, you have to fulfill the following criteria:
- you must be over 18 years of age and be of sound mind,
- you must be of good character and you should have a satisfying knowledge of English, Welsh, or Scottish Gaelic (there are exemptions to elderly people),
- you must be willing and able to pass the UK government's Life in the UK test before you submit your application

The additional criteria are different depending on the specific circumstances of each case.
Naturalisation after five (5) years in the UK
If you are not married to a British citizen or a person settled in the UK, you will need to satisfy the following residence requirements over the last five years in order to apply for naturalisation:
- you must have been living in the UK for the five years before the application reaches the Home Office
- during the five year period, you must not have been outside the UK for more than 450 days (15 months)
- during the last 12 months, you must not have been outside the UK for more than 90 days (three months)
- during the last 12 months, you must have held Permanent Residence (ILR)
- during the five year period, you must not have been in breach of the immigration laws.
Naturalisation after three (3) years in the UK as a Spouse of a UK Citizen
The criteria for naturalisation as a spouse of a British citizen or a person settled in the UK should be met in full:
- you have been living in the UK for the three years before the application reaches the Home Office,
- during this three year period, you must not have been outside the UK for more than 270 days (nine months),
- during the last 12 months, you must not have been outside the UK for more than 90 days (three months),
- on the date that your application is received by the Home Office, your stay in the United Kingdom must not be restricted by any time limit under the UK immigration laws, that is, you must hold ILR, 
- during the three year period, you must not have been in breach of the immigration laws.