Although the terms objective and purpose are mostly used to mean the same and are used interchangeably but under International Auditing Standards (ISAs) the purpose of audit and objective of audit is NOT the same thing.
Under ISAs the term purpose of audit simply means why audit is conducted. Whereas objective of audit means what auditor is bound to achieve.
Purpose of audit
According to ISA 200 para 3:
The purpose of an audit is to enhance the degree of confidence of intended users in the financial statements.
Objective of audit
According to International Framework for Assurance Engagement para 11:
The objective of a reasonable assurance engagement is a reduction in assurance engagement risk to an acceptably low level in the circumstances of the engagement as the basis for a positive form of expression of the practitioner’s conclusion.
If we take the above sentence in terms of audit engagement then we can say that the objective of an audit engagement is to reduce audit risk to an acceptably low level so that opinion can be expressed in the positive form of expression (which in also termed as positive assurance).
In simple words the objective of audit is to express an opinion in a positive form of expression
Is it safe to interpret or equate the terms “reasonable assurance engagement” with “audit engagement”?
According to ISA 200 para 5:
As the basis for the auditor’s opinion, ISAs require the auditor to obtain reasonable assurance about whether the financial statements as a whole are free from material misstatement, whether due to fraud or error.
Or simply, auditor is duty bound to obtain “reasonable assurance” under an audit engagement. Therefore audit engagement is a reasonable assurance engagement and thus the objective of reasonable assurance engagement (to reduce engagement risk to an acceptably low level) is also the objective of audit engagement.
It gets further clear in the same paragraph i.e. ISA 200 para 5 where it is stated:
Reasonable assurance is a high level of assurance. It is obtained when the auditor has obtained sufficient appropriate audit evidence to reduce audit risk to an acceptably low level.
Also in ISA 200 para 11(a)
In conducting an audit of financial statements, the overall objectives of the auditor are to obtain reasonable assurance…
This clarifies that auditor is required obtain reasonable assurance which is obtained by reducing audit risk to an acceptably low level. Therefore the ultimate objective of audit engagement is to reduce audit risk to an acceptably low level.
The increased degree of confidence is the resultant benefit of audit engagement and NOT the objective of audit engagement