Marriage to a British citizen does not automatically grant the non-UK spouse British citizenship. British citizenship is attained by marriage through the process of naturalisation. This requires the non-UK spouse to meet eligibility criteria under the nationality rules and make a citizenship application to the Home Office.

According to UK immigration law, those who are married to or in a civil partnership with a UK national do not automatically acquire British citizenship. Therefore, those who wish to remain in the UK permanently with their British spouses or partners may consider applying for British naturalization.

You can apply for UK citizenship by marriage if you're married to a British citizen or a person settled in the UK and have lived in the UK for at least 3 years. You can apply for British citizenship as soon as you have Indefinite Leave to Remain (ILR) or “Settled Status” in the UK. You do not need to wait for 12 months after ILR.