When I was born my Mum and Dad weren't married so my birth certificate was in my Mum's maiden name. They got married when I was 2 and changed my surname to my Dad's - for which I got another birth certificate. I used my Dad's name all my life and got my NI number etc in that name.I would like to change everything back to my Mum's maiden name and have pretty much changed everything except my NI number, doctors records, tax credits, child benefit etc and was wondering if anyone knows if I have to do it 'officially' or if I can just advise them that I am going back to my birth name?