Niam

How do I register as a UK citizen by descent, I'm over 18.
Mother naturally born with US and UK citizenship (in UK to deployed US citizens).

BritInParis

What year was your mother born? When you say 'deployed', do you mean that your grandparents were serving in the USAF or similar?

Niam

Exactly, her father was serving in the UK and her mother went with, so she was born on UK soil hence the UK citizenship with the US. She has birth certificates for both nations. She was born in 1964.

HKG3

Were you born before or after the 1 January 1983?

christmasoompa

Just to clarify for the sake of anybody reading, being born on UK soil doesn't make one a UK citizen. The US is fairly rare as a country that grants citizenship to anybody born there and the UK doesn't do the same.

Good luck with your application, I'm sure BIP will steer you right, he's a star.

Niam

After 1983, and I am over 18

BritInParis

If your mother was born before 1983 and you were born after 1983 and your maternal grandfather did not hold diplomatic immunity at the time your mother was born then you are already a British citizen and only need to apply for your British passport.

https://www.gov.uk/overseas-passports

Niam

Awesome thanks! That's a lot simpler than I imagined

HKG3

Please note that being a British Citizen by descent means that you cannot automatically pass on your British Citizenship to your child born outside of the UK.