Where you require an applicant to provide documentary evidence, you should write to the applicant informing them that it has not been possible to establish their identity as required by law and asking them to supply documentary evidence to prove their identity in order to register.1
You should be mindful of the impact of this on the applicant, for example, the elderly or vulnerable or those for whom English is not their first language.
The letter should list the types and quantity of evidence that must be provided. It may also set a deadline date for the applicant to respond. A deadline will be helpful when deciding to reject an application because no response has been received. The time given to respond is at your discretion; however, it should allow the applicant reasonable time to locate and provide the documents required.