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Internal Audit: Definition, Key Roles and How to Conduct an Audit

Written by Nikki Young | Mar 13, 2026 9:47:11 AM

Internal audit has fundamentally transformed from a back-office compliance function into a strategic business partner that drives organizational value, manages enterprise-wide risks, and enhances governance across all business units. 

As organizations navigate increasingly complex regulatory landscapes, technology changes, and evolving stakeholder expectations, internal audit functions are being reimagined to provide forward-looking insights, analytical rigor, and proactive risk management support that extends far beyond traditional compliance checking.

What is Internal Audit?

Internal auditing is defined by the Institute of Internal Auditors (IIA) as an independent, objective assurance and consulting activity designed to add value and improve an organization's operations. 

In providing assurance, internal audit contributes to an organization’s Governance, Risk, and Compliance (GRC) framework, which aims to ensure an organization is adhering to both internal and external regulations and requirements. 

What differentiates internal audit from routine compliance or financial functions is its systematic, disciplined approach to evaluating and improving the effectiveness of risk management, control, and corporate governance processes. 

Why is Internal Audit Important?

Organizations face an overwhelming array of threats spanning financial, operational, compliance, strategic, reputational, cybersecurity, and sustainability dimensions. Without an independent assurance function like internal audit, senior management and governing bodies lack the objectivity and comprehensive visibility needed to understand whether these risks are being appropriately identified and managed.


Internal Audit, the Business, and Other Lines of Defense

The Three Lines Model provides a framework for understanding how different functions within an organization share responsibility for managing risks and maintaining internal controls. 

The first line of defense consists of business units and operational functions that directly manage day-to-day risk through their execution of processes, implementation of controls, and monitoring of operations. 

The second line of defense encompasses risk management, compliance, and internal control functions that provide oversight, guidance, and monitoring of first-line risk management activities. 

The third line of defense is represented by the internal audit function. What distinguishes internal audit is its organizational independence from management. Internal auditors do not manage risks, do not make management decisions, and do not operate the controls that other functions have established. 

Internal audit must carefully balance its interaction with the business in order to function as trusted advisors and strategic partners while simultaneously maintaining the independence necessary to render unbiased assessments.

Understanding the Different Types of Internal Audit

Financial

Financial audits are probably what most people think of when they hear “audit”. Financial audits typically examine the effectiveness of internal controls surrounding financial reporting processes, the integrity of accounting systems and records, and the appropriateness of significant financial transactions and account balances. 

Compliance and Regulatory Auditing

Compliance audits focus on assessing whether the organization is adhering to applicable laws, regulations, internal policies, and contractual obligations. 

By conducting rigorous compliance audits, internal audit functions help organizations avoid costly penalties and regulatory actions while positioning organizations to demonstrate to regulators that appropriate oversight mechanisms are in place.

Operational Auditing

Operational audits evaluate the efficiency and effectiveness of an organization's operational performance. These audits often result in recommendations that directly impact the bottom line by identifying cost reduction opportunities, process improvements that enhance productivity, and resource allocation changes that improve effectiveness.

Information Technology and Cybersecurity Auditing

Information technology audits examine the security and effectiveness of an organization's information technology infrastructure, applications, operating systems, databases, and enterprise systems. These audits have taken on heightened significance in recent years as cybersecurity threats have become more sophisticated and damaging.

Environmental, Social, and Governance (ESG) Auditing

Environmental, social, and governance (ESG) auditing evaluates an organization's alignment with ESG standards and identifies areas for improvement in sustainability practices, social responsibility initiatives, and governance effectiveness. 

The growth of ESG auditing reflects the intensifying focus of investors, regulators, customers, and other stakeholders on corporate sustainability and responsible business practices. 

The Evolution of Internal Audit

Historically, internal audit was viewed as a compliance function responsible for ensuring that policies were followed, irregularities were detected, and regulatory requirements were met. 

In recent years, internal audit has evolved from check-box compliance toward a broader, more strategic advisory role that drives process improvements, enhances governance, and helps organizations navigate complex risk landscapes.

This evolution reflects recognition that organizations face increasingly sophisticated threats that extend far beyond simple compliance issues. 

How to Plan and Conduct Internal Audits in Companies

How to Plan Internal Audits

Effective internal audit planning begins with comprehensive risk assessment and strategic alignment to ensure that the annual audit plan is aligned with organizational priorities and focused on areas of greatest risk and concern.

Frameworks and Standards Guiding Internal Audit Planning

There are a number of frameworks that can be used in planning an internal audit: 

  • The IIA’s Global Internal Audit Standards (a mandatory component of the International Professional Practices Framework (IPPF)) specify that internal audit functions must develop and maintain a risk-based internal audit plan that is approved by the audit committee or board, communicates how audit resources will be allocated to address the organization's most significant risks, and is flexible enough to address emerging threats and changing organizational priorities.
  • ISO 19011 guides organizations on establishing audit program objectives, defining the scope and frequency of audits, training and evaluating auditors, and continuously improving audit processes.
  • The Public Company Accounting Oversight Board (PCAOB) provides guidance on external auditors' consideration of the internal audit function, addressing the competence and objectivity of internal auditors and describing how external auditors should evaluate the effectiveness of internal audit work.
  • The Sarbanes-Oxley (SOX) framework requires organizations to maintain effective internal controls over financial reporting and have those controls audited by external auditors. This requirement has driven organizations to establish robust internal audit functions that help ensure financial reporting controls are adequate and operating effectively. 
  • The COSO Internal Control-Integrated Framework, which provides comprehensive guidance on designing, implementing, and evaluating internal control systems, has similarly shaped how organizations conceptualize the audit planning process.

How to Conduct Internal Audit Fieldwork

Once an audit engagement has been planned and approved, internal auditors conduct fieldwork to gather evidence, test controls, and develop findings that support conclusions about the adequacy and effectiveness of governance, risk management, and control processes. 

The core of audit fieldwork involves conducting interviews with company personnel to understand processes and controls, reviewing documentation and systems, performing testing procedures to evaluate control effectiveness, and gathering evidence to support audit observations and conclusions. 

Testing procedures constitute a significant component of audit fieldwork and involve examining samples of transactions or records to evaluate whether controls operated effectively during the period reviewed. 

As fieldwork progresses, auditors conduct exit interviews with management to discuss their observations, validate their understanding of processes, and allow management to respond to preliminary findings and/or correct any misunderstandings.

How Internal Audit Teams Are Organized

Larger organizations with complex operations often have dedicated teams focused on different types of audit. Smaller organizations typically have more generalized audit teams where auditors develop broad skills across multiple audit domains. 

During the audit planning process, internal audit might use a risk matrix to prioritize identified risks based on likelihood of occurrence and potential impact. Risks rated as high impact and high likelihood are typically prioritized in the audit plan, with audit engagements scheduled to evaluate controls in those high-risk areas. Moderate-risk areas might be scheduled for audit less frequently, with potentially less extensive scope of work. Lower-risk areas might receive audit attention on less frequent cycles or receive limited scope audit work.

Internal audit teams usually employ a combination of recurring audit engagements scheduled on established cycles and ad hoc audits addressing specific concerns or emerging risks.

Differentiating Internal and External Audit

Purpose and Audience

The most fundamental distinction between internal and external audit relates to their respective purposes and primary audiences. Internal audit focuses on helping the organization enhance risk management, strengthen controls, and improve operational effectiveness

External audit, by contrast, focuses on providing compliance-oriented assurance to external stakeholders regarding the organization's financial condition, financial reporting accuracy, and adherence with regulatory requirements and independent audit standards. 

Scope and Focus of Audit Work

The scope of internal audits is typically determined by management and the audit committee, reflecting the organization's priorities for internal audit attention and strategic focus areas. 

The scope of external audits is determined by applicable accounting standards, regulatory requirements, and the terms of the external audit engagement. Generally, external audits focus on examining financial statement accounts and disclosures that are material to users' understanding of the organization's financial condition. 

Frequency and Timing of Audit Work

Internal audits are typically conducted on schedules determined by organizational risk assessment, with recurring audits scheduled based on risk prioritization

External audits are generally performed on annual or near-annual schedules, as external stakeholders expect consistent, periodic assurance regarding financial statement accuracy and regulatory compliance. 

Independence and Objectivity Requirements

Internal auditors must be independent of the functions they audit, meaning they cannot audit processes for which they hold management responsibility and must maintain professional distance from management to preserve unbiased judgment. 

External auditors must be independent of the organization, meaning external audit firms cannot simultaneously provide services that would compromise their ability to render objective opinions on financial statements. 

What Does a Typical Internal Audit Team Look Like?

The Chief Audit Executive (CAE) is accountable for leading the internal audit function and serves as the primary representative of internal audit to senior management, the audit committee, and the board, carrying responsibility for positioning internal audit as a trusted advisor and strategic partner.

Beyond the CAE role, typical internal audit functions include specialized audit roles focused on different domains such as financial audit, operational audit, IT audit, and compliance audit. Senior auditors or audit managers typically oversee specific audit engagements, while in-charge auditors lead execution of individual audit engagements, and junior or staff auditors perform detailed testing and evidence collection. 

Internal Audit Team Size Across Different Organization Sizes

The size of internal audit functions varies dramatically across organizations based on organizational complexity, threat profile, regulatory requirements, and resource availability.

Modern Auditor Skills and Competencies

The expectations of auditor competencies have undergone significant transformation in recent years to reflect the evolving nature of business threats and organizational requirements. 

Historically, internal auditors were primarily expected to possess strong technical audit skills including understanding of audit standards and procedures, financial acumen, and ability to conduct interviews and document analysis. 

The emerging skillsets highly valued in modern internal auditors include data analytics and data literacy enabling auditors to analyze large data sets to identify anomalies and patterns, artificial intelligence literacy to understand how AI systems operate and what risks they present, cybersecurity domain knowledge to assess technology security controls, and sustainability expertise to evaluate environmental and social governance practices.

And because internal audit now increasingly functions as a strategic advisor rather than simply a compliance checker, auditors must also possess strong soft skills including communication abilities, relationship-building capacity, critical thinking, emotional intelligence, and change management understanding.

Who Does the Internal Audit Team Report To?

The reporting structure of the internal audit function is critical to preserving independence and objectivity and is explicitly addressed in internal audit standards and governance frameworks.

Internal auditors maintain a dual reporting relationship: functionally reporting to the audit committee or board and administratively reporting to senior management, typically the Chief Executive Officer or Chief Financial Officer. 

This administrative reporting line has generated ongoing debate within the internal audit profession regarding whether this arrangement creates the appearance of compromise to internal audit independence and creates potential for bias toward financial audit areas within the CFO's domain and might create reluctance for internal audit to report negative findings regarding financial function controls or CFO decision-making.

The Audit Committee Relationship

The relationship between the Chief Audit Executive and the audit committee chair is fundamental to the success of the internal audit function and the effectiveness of the audit committee's oversight role. The audit committee is typically composed of board members who are independent from management and possess financial, governance, or audit expertise. 

The CAE must ensure that the audit committee receives timely, clear communication regarding significant findings and risks, but must do so in ways that preserve management's ability to address findings and implement improvements without excessive external pressure.

The audit committee must avoid becoming too involved in internal audit decisions regarding specific audit engagements, as this involvement could compromise the audit committee's oversight role. However, the audit committee must be sufficiently engaged to understand the internal audit function's strategy, assess audit quality and relevance, and ensure that audit results are appropriately considered in the audit committee's oversight of organizational risks and controls. 

What is Internal Audit Software and How Can Companies Use It ?

Internal audit software refers to technology platforms that systematically support execution of internal audit functions, including planning, conducting engagements, documenting findings, and reporting results. 

The most comprehensive category of internal audit software encompasses Governance, Risk, and Compliance (GRC) platforms that integrate risk management, compliance management, audit management, and internal control assessment capabilities into unified systems. 

Rather than maintaining separate systems for financial audit, operational audit, regulatory adherence monitoring, and risk management, GRC platforms attempt to provide integrated data and workflows that enable different functions to share information and coordinate their efforts. This integration provides significant value by eliminating information silos, enabling more efficient use of audit and compliance resources, and providing executives and boards with comprehensive views of organizational threats and control effectiveness.

Why Internal Audit Software Is Important

Effective audit management requires managing substantial volumes of information including audit plans, risk assessments, audit documentation, control testing evidence, findings, management action plans, and follow-up tracking. Without appropriate technology infrastructure, internal audit teams become dependent on manual processes including spreadsheets, email, and unstructured folders for managing audit work, resulting in inefficiency, inconsistent documentation, and difficulty integrating audit information with other organizational systems. 

Internal audit software solves these challenges by providing structured processes for planning audits, assigning work, collecting evidence, enabling continuous auditing and monitoring capabilities (using specific audit analytics software), documenting findings, routing communications, and consolidating results.

Internal Audit Software and Platforms

Rather than relying on fragmented spreadsheets, email communications, and manual workpaper management, internal audit software and platforms consolidate audit workflows into centralized systems that provide real-time visibility, automated evidence collection, and AI-powered insights.

  • AuditBoard centralizes the complete audit lifecycle from planning through follow-up, with AI-powered capabilities that automate manual tasks such as evidence gathering, test selection, and report generation.
  • Workiva unites internal audit, risk management, ESG assurance, and financial reporting within a single environment, enabling internal auditors to maintain data integrity and establish single sources of truth for audit evidence
  • Onspring uses process automation and real-time analytics capabilities designed to align with the IIA standards and COSO framework, enabling audit teams to manage planning, fieldwork, findings, and reporting within integrated applications.
  • Diligent Audit offers continuous assurance and end-to-end automation spanning risk assessment, audit execution, and follow-up phases, using AI-powered natural language testing tools.
  • TeamMate+ Audit provides comprehensive end-to-end audit workflow capabilities from annual planning through fieldwork execution to reporting and follow-up, and integrates data-driven insights throughout the audit process.
  • Supervizor offers an audit analytics platform that enables continuous data monitoring across the organization, risk identification and prioritization, and provides 350+ pre-built routines, covering high-risk processes.  

How Does Internal Audit Rely on Internal Control to Strengthen Risk Management?

Internal audit and internal control (or whichever department(s) holds second line responsibility for management’s assessment of risk if no internal control department exists) represent complementary but distinct organizational functions that together support effective risk management and governance. 

Management is responsible for establishing and maintaining internal controls appropriate to the organization's risk profile and strategic objectives.

Internal audit's role is to evaluate whether the control environment that management has established is sufficient to mitigate identified threats, whether specific control activities are operating effectively to prevent or detect errors and fraud, and whether monitoring activities are occurring to verify ongoing control effectiveness. 

Effective risk management requires integration of management's control implementation, management's monitoring activities, and internal audit's independent assurance. When these functions work effectively together, organizations benefit from comprehensive identification of emerging risks, appropriate design and implementation of controls to mitigate those risks, management activities to verify control effectiveness, and independent assurance providing confidence that risks are being appropriately managed.