A permanent audit files contains information that is relevant for more than one financial year i.e information that is useful to the auditor for more than one financial year and is not specific to a single financial period. For example the letter of engagement is contained in a permanent audit file. The engagement letter contains the terms of the contract between the auditor and the client. This information is required by the auditor in every financial period.
On the other hand the current audit file contains information that is relevant for the current financial period under audit. For example confirmations obtained from debtors are only relevant for the specific financial period being audited.
Audit working papers provide evidence on the audit objective that the auditor was testing, information obtained in relation to that audit objective and the conclusion drawn by the auditor as supported by the evidence documented in the working papers.