Where an applicant cannot prove their identity by providing documentary evidence to the type and quantity required by the exceptions process, you should write to them informing them of this and asking them to provide an attestation in support of their application.
Attestation is the final option in the verification of identity process. Applicants can only use attestation to establish their identity once all the other verification stages of DWP matching, local data matching (where appropriate) and the exceptions process have been undertaken and it has not been possible to verify their identity.1