Internal Audit vs External vs Statutory Audit: Differences & Scope

Internal Audit vs External vs Statutory Audit: Quick Comparison

What Is Internal Audit?

Internal audit is an independent and objective assurance and advisory function that evaluates an organization’s risk management, internal controls, governance, compliance, and business processes.

Unlike an audit limited to financial statements, internal audit can cover almost any area within the organization’s audit universe.

Common Internal Audit Areas

Under Section 138 of the Companies Act, 2013, prescribed classes of companies are required to appoint an internal auditor to conduct an internal audit of the company’s functions and activities.

Objectives of Internal Audit

• Identify and assess business risks
• Evaluate the design and effectiveness of controls
• Identify control weaknesses
• Improve business processes
• Strengthen governance
• Assess compliance
• Provide assurance to management and the Board
• Track corrective actions
• Support continuous improvement

What Is External Audit?

An external audit is an independent examination performed by an auditor who is not part of the organization’s internal audit function. For financial statement audits, the auditor’s overall objectives and responsibilities are defined under the applicable Standards on Auditing (SAs).

The term external audit describes the auditor’s relationship with the organization. It does not, by itself, define the legal basis or exact purpose of the audit.

Depending on the engagement, an external audit or assurance engagement may cover:

• Financial statements
• Internal controls
• Compliance
• Cybersecurity
• Information security
• Regulatory requirements
• Other defined subject matter

The exact objective and scope depend on the engagement.

What Is Statutory Audit?

A statutory audit is an audit required by applicable law or regulation, with its scope, auditor responsibilities, and reporting requirements determined by the relevant statutory and professional framework.

For companies governed by the Companies Act, 2013, provisions relating to the appointment and responsibilities of statutory auditors are contained in the Act, including:

• Section 139 – Appointment of auditors
• Section 143 – Powers and duties of auditors
• Section 144 – Services not to be rendered by auditor

Internal Audit vs External vs Statutory Audit: Complete Comparison

Difference Between Internal Audit and External Audit

Difference Between Internal Audit and Statutory Audit

External Audit vs Statutory Audit

Scope of Internal Audit

Internal audit can have a broader scope because its audit universe can extend across financial, operational, technology, compliance, risk and governance areas.The scope and periodicity of individual audits are typically organized through an audit program, which helps define the audit areas, objectives, procedures, timing, and resources required.

Scope of External Audit

The scope of external audit depends on the specific engagement. For a financial audit, the auditor may examine:

• Financial statements
• Accounting records
• Material transactions
• Supporting evidence
• Relevant controls
• Accounting estimates
• Financial disclosures

For a cybersecurity or compliance assurance engagement, the scope may instead focus on specific technology or control areas.

Scope of Statutory Audit

The scope of statutory audit is determined by:

• Applicable law
• Accounting standards
• Auditing standards
• Financial reporting framework
• Regulatory requirements
• Audit objectives

Who Is Responsible for Each Audit?

Internal Audit

Internal audit evaluates and reports on risks and controls. Management remains responsible for designing controls, operating controls, managing risks, and implementing corrective actions.

External Audit

The external auditor is responsible for performing the engagement in accordance with applicable requirements and reporting its conclusions.

Statutory Audit

The statutory auditor has responsibilities prescribed by applicable law and auditing standards. Section 143 of the Companies Act, 2013 sets out important powers and duties of auditors.

When Is Each Audit Required?

Internal Audit in India

Internal audit is not automatically mandatory for every company simply because it is incorporated in India. Section 138 of the Companies Act, 2013 applies to prescribed classes of companies. See our guide: Internal Audit Applicability in India.

Statutory Audit

Statutory audit requirements arise from the applicable law. For companies governed by the Companies Act, 2013, Sections 139 and 143 deal with appointment and duties of statutory auditors.

External Audit

There is no single universal answer because external audit is a broad term. An external audit may be required by law, regulator, contract, investors, lenders, customers, or voluntarily commissioned by management.

Practical Examples

How Internal and External Audits Work Together

Internal and external audits should not be viewed as competing functions. They can provide complementary forms of assurance.

Internal Audit vs External vs Statutory Audit: Decision Guide

Internal Audit and External Audit Classification Checklist

• ☐ Who is performing the audit?
• ☐ Is the auditor independent of management?
• ☐ Why is the audit being performed?
• ☐ Is it required by law?
• ☐ What is the audit objective?
• ☐ What is the scope?
• ☐ Is the focus financial, operational, technological, compliance-related, or broader?
• ☐ Who will receive the report?
• ☐ Are corrective actions expected to be tracked?
• ☐ What legal or professional requirements apply?

Managing Internal Audit Findings After the Audit

An internal audit report summarizes the audit scope, findings, risks, recommendations, management responses, and agreed corrective actions. An audit report is not the end of the audit process. Once findings are identified, teams still need to:

• Assign ownership
• Define corrective actions
• Set due dates
• Collect supporting evidence
• Monitor overdue actions
• Validate remediation
• Maintain an audit trail
• Close observations

This is where many organizations move from an audit reporting problem to an audit remediation problem.

Manage the Complete Internal Audit Lifecycle With ASPIA

ASPIA helps organizations manage the complete internal audit lifecycle—from planning and evidence collection to observations, remediation, validation, and closure.

The objective is to move findings through: Identification → Ownership → Remediation → Validation → Closure

Frequently Asked Questions

Conclusion

Internal audit, external audit, and statutory audit serve different purposes and should not be treated as interchangeable terms.

The simplest distinction is:

• Internal Audit → Focuses on risks, controls, governance, compliance, and improvement
• External Audit → Provides independent assurance through an external party
• Statutory Audit → Performed because applicable law or regulation requires it

The most important distinction is between external and statutory: external describes who performs the audit; statutory describes why the audit is required.

Ultimately, an audit creates value not merely when a report is issued, but when the resulting findings are assigned, remediated, evidenced, validated, and closed.