Fundamental Principles of Assurance Engagements
An assurance engagement involves three essential parties: the practitioner (governed by professional competence), the responsible party (accountable for the subject matter), and the intended users (identified by agreement).
The subject matter is what's being evaluated—like financial statements—while the subject matter information is the outcome of this evaluation against specific criteria. For example, in a financial audit, the financial statements themselves are the subject matter information.
When gathering evidence, auditors must consider both sufficiency (quantity) and appropriateness (quality). Remember that more evidence may be needed when risk is higher, but simply getting more low-quality evidence doesn't compensate for poor quality. Evidence is more reliable when:
- Obtained from outside sources
- Generated internally under effective controls
- Directly obtained by the auditor
- In written/documentary form
- From original rather than copied sources
Pro Tip: Professional skepticism is crucial throughout an engagement. Maintaining a questioning mindset helps you avoid overlooking suspicious circumstances and strengthens your ability to gather appropriate evidence.
Assurance engagements vary by level and structure. Reasonable assurance engagements (like audits) provide high assurance with positive opinions, while limited assurance engagements (like reviews) offer moderate assurance with negative opinions. The procedures differ significantly—audits require more extensive procedures beyond inquiry and analytics.
The structure can be either attestation-based (practitioner evaluates assertions made by the responsible party) or direct (practitioner directly reports on the subject matter).
Non-assurance engagements include agreed-upon procedures (reporting findings without conclusions), compilations (organizing financial information without assurance), tax services, and management consulting. These services don't provide the same level of confidence as assurance engagements.
Professional standards are established by various boards under the International Federation of Accountants (IFAC), with corresponding Philippine Standards covering auditing (PSAs), review engagements (PSREs), assurance engagements (PSAEs), related services (PSRSs), and quality control (PSQCs).











