An audit trail refers to a situation where it is possible to relate “one-to-one” basis, the original input along with the final output. The work of an auditor would be hardly effected if audit trail is maintained, i.e. if it were still possible to relate, on a “one-to-one” basis, the original input with the final output. A simplified representation of the documentation in a manually created audit trail. The particular credit notes may be located by the auditor at any time s/he may wish to examine them, even months after the balance sheet date. S/he also has the means, should s/he so wish, of directly verifying the accuracy of the totals and sub-totals that feature in the control listing, by reference to individual credit notes. S/he can, of course, check all detailed calculations, casts and postings in the accounting records, at any time.
In first and early second –generation computer system, such a complete audit trail was generally available, no doubt, to management‟s own healthy skepticism of what the new machine could be relied upon to achieve-an attitude obviously shared by the auditor. In such a system:
The output itself is as complete and as detailed as in any manual system.
The trail, from the beginning to the end, is complete, so that all documents may be identified by located for purpose of vouching, totaling and cross referencing.
Any form of audit checking is possible, including depth testing in either direction. In case audit trail is missing, the auditor employs Computer Assisted Audit Techniques (CAAT) to ensure the validity of accounting data.