For the initial Decision in Principle application you don't need to provide any documents. However, once you're ready to move ahead with advice and a formal application, we might need to see some documents to verify your identity.
The documents we accept as a proof of identity are listed here:
Valid UK Passport
Valid UK Driving License — Photo card (Full or Provisional)
Valid Non-UK passport or National ID Card
HM Forces ID Card
Police Warrant Card
UK Firearms License or Shotgun Certificate – current
Current State Pension notification letter
Current Benefits Agency letter
Current years HMRC Tax Code Notification
Current Blue Disabled Drivers Pass
Identity Card by Electoral Office of Northern Ireland