The auditor should obtain sufficient appropriate audit evidence through the performance of compliance and substantive procedures to enable him to draw reasonable conclusions there from on which to base his opinion on the financial information.
Compliance procedures are tests designed to obtain reasonable assurance that those internal controls on which audit reliance is to be placed are in effect.
Substantive procedures are designed to obtain evidence as to the completeness, accuracy and validity of the data produced by the accounting system.
They are of two types:
(i) tests of details of transactions and balances;
(ii) analysis of significant ratios and trends including the resulting enquiry of unusual fluctuations and items.