What details do I need to register for the Charities Online service?
You'll need your:
HMRC Charities Reference number which usually starts with a letter followed by some numbers
postcode (unless you say that your address is abroad)
the last 4 digits of your organisation’s bank account number - for charities and Community Amateur Sports Clubs (CASCs) that were recognised or registered by HM Revenue and Customs (HMRC) before April 2013
your customer account reference - for charities and CASCs that were recognised or registered by HMRC after April 2013. This is a 10 digit number shown on the letter sent to you by HMRC when your charity application or CASC registration has been accepted