Internal Audit Meaning: Definition, Types and Process

Internal audit is an organization's own independent, objective review of how well it manages risk, runs its controls and governs itself. It is carried out by people inside the company (or working for it) who report to the board or audit committee rather than to the managers whose work they examine. Its purpose is not to catch people out. It is to help the organization reach its goals with fewer surprises.

Below we explain the official definition in plain words, what internal auditors actually do day to day, the types of audits, the stages of a typical engagement, and how internal audit differs from external audit. We also show what an internal audit looks like in a security and compliance setting, because that is where many of our readers meet it first.

TL;DR

• Internal audit is an independent, objective assurance and consulting activity that helps an organization improve its operations, risk management, controls and governance.
• Internal auditors examine processes, interview teams, uncover risks and recommend improvements, then follow up on what management does about them.
• Common types include compliance, financial, operational, performance, IT and environmental audits.
• A typical engagement runs through planning, fieldwork, reporting and monitoring.
• External audit focuses mainly on financial statements. Internal audit has a wider, risk-based scope across the whole organization.

Table of Contents

• What internal audit means
• What internal auditors do
• Types of internal audits
• The stages of an internal audit
• Internal audit vs. external audit
• How internal audit supports risk, controls and governance
• Internal audit in security and compliance
• Our perspective
• Put your audit evidence to work
• FAQ
• Sources

What internal audit means

The most quoted definition comes from the Institute of Internal Auditors (IIA). It describes internal auditing as an independent, objective assurance and consulting activity designed to add value and improve an organization's operations. It adds that the activity helps an organization accomplish its objectives by bringing a systematic approach to evaluating and improving risk management, control and governance.

Each word in that definition carries weight:

• Independent means auditors are positioned so management cannot steer their conclusions. ACCA stresses that internal audit needs board or audit-committee authorization, independent positioning and oversight so auditors can work without interference.
• Objective means the auditor's judgment rests on evidence, not on relationships or preferences.
• Assurance means giving the board and executives confidence that things work as described.
• Consulting means advising on how to fix or improve something, not only reporting that it is broken.

The IIA's 2024 Global Internal Audit Standards extend the idea. They say internal auditing strengthens an organization's ability to create, protect and sustain value through independent, risk-based, objective assurance, advice, insight and foresight. The standards are organized into five domains: purpose; ethics and professionalism; governing the internal audit function; managing the function; and performing audit services, as laid out on the IIA's standards page.

In the UK, ICAEW offers a more everyday framing: internal audit is an independent health check of business processes and controls, looking at whether they are well designed and work efficiently, so the business can improve them. That is a useful mental picture. Think of a routine medical check-up for how the company operates.

What internal auditors do

The IIA describes internal auditors as trusted advisers who examine processes, interview teams, analyze operations, uncover risks, identify inefficiencies and recommend improvements. In practice the work falls into a few repeating activities:

1. Testing controls. Does the approval step, access restriction or reconciliation exist, and does it operate as designed?
2. Checking compliance. Are laws, regulations, contracts and internal policies being followed?
3. Reviewing information. Are financial and operating reports accurate and timely?
4. Evaluating risk management. Has the organization identified its significant risks and does it respond sensibly?
5. Advising. Should a new system, process or vendor relationship be built with better safeguards from the start?

In the United States, the auditing standard SAS 128 from the AICPA lists the kinds of work an internal audit function may perform. It includes work over governance, significant risk exposures, fraud detection, control design and operation, financial and operating information, operating activities, and compliance with laws, regulations and internal requirements. The same document says objectives and scope typically include assurance and consulting activities that evaluate and improve governance, risk management and the effectiveness of internal control.

The OCC, which supervises national banks in the US, adds detail on what effective programs look like. It says they document tests, findings and corrective actions, assess the accuracy and timeliness of reporting, review how assets are safeguarded, test controls, evaluate compliance with law and policy, and advise on significant initiatives and third-party risk.

A simple example

Imagine a company that pays suppliers through an accounts payable team. An internal auditor might pick a sample of payments from the past quarter and check three things: was each invoice approved by someone with the right authority, did the payment match a purchase order, and could one person both create a vendor and release payment to it? If the last answer is yes, that is a control gap. The auditor writes it up, ranks its significance, agrees an action plan with the finance manager and returns later to confirm the gap was closed.

Nothing in that example is about blame. It is about finding the weak point before an error, a fraud or an external examiner does.

Types of internal audits

There is no single universal list, but the categories below appear consistently. Investopedia's overview names compliance, financial, environmental, technology or IT, operational and performance audits. Many readers collapse these into three broad families, which is how the question "what are the three types of internal audits?" is usually answered:

Two specific types deserve a closer look:

• Compliance audits review adherence to rules and policies, whether they come from a regulator, a customer contract or the company's own handbook.
• Performance audits assess results against metrics that management has set, for example how quickly a service desk resolves tickets.

IT and technology audits sit across all three families. They look at access management, change control, backup and recovery, vendor oversight and data protection. Even something as ordinary as how a multinational company manages its mobile service contracts and device security can fall within scope, which is why a provider offering centralized mobile service security with compliance and access features is the kind of system an auditor may ask about.

The stages of an internal audit

Investopedia describes four common stages: planning, auditing, reporting and monitoring. The IIA's standards describe the same arc in more formal terms: planning the engagement, developing findings and conclusions, collaborating with management on recommendations or action plans, and communicating throughout and after the engagement.

Put together, a typical engagement looks like this:

1. Planning. The audit team agrees the objective and scope, learns the process, identifies the risks that matter most and decides which controls to test. Most functions work from an annual audit plan that ranks areas by risk.
2. Fieldwork. Auditors gather evidence: documents, system data, samples of transactions, walkthroughs and interviews. They compare what they find to the criteria, which might be a policy, a regulation or a good-practice framework.
3. Findings and conclusions. Where evidence differs from the criteria, the auditor documents the condition, the cause and the effect, and rates the significance.
4. Reporting. The report goes to management and, for significant matters, to the audit committee. Management responds with action plans and owners.
5. Monitoring. Auditors track whether the agreed actions were completed and whether they fixed the underlying problem.

Communication runs through all five steps. A good audit has no surprises at the closing meeting, because the auditor has shared emerging issues as they appeared.

What the auditee can do to help

If your team is about to be audited, these habits shorten the engagement and improve the outcome:

• Keep policies, procedures and evidence in one organized, current place.
• Name a single point of contact who can pull documents quickly.
• Tell the auditors about known weaknesses early. It builds credibility.
• Agree owners and realistic dates for each action, not aspirational ones.

Internal audit vs. external audit

These two are often confused because both involve auditors and reports. The difference is in who they serve and how wide they look.

The US Federal Housing Finance Agency explains that internal auditors generally have broader responsibilities than external auditors, including controls over processes unrelated to a financial-statement audit. External audit is performed by an independent outside auditor and primarily focuses on financial statements and related controls over financial reporting.

The OCC puts the relationship this way: external-audit programs complement internal auditing by giving management and the board an independent view of financial-statement reliability and of controls over financial reporting, while internal auditing covers the wider control and operations environment.

The two can also cooperate. The AICPA's guidance indicates that external auditors may use internal audit's work, but only when the internal function's responsibilities and work are relevant to financial reporting and have been appropriately evaluated, as set out in SAS 128. Strong internal audit work can therefore reduce duplicated effort at year end.

How internal audit supports risk, controls and governance

Internal audit sits at the center of three connected disciplines.

Risk management. Auditors do not own the organization's risks, management does. Auditors assess whether the risk process works and whether responses are adequate. The OCC describes internal audit as the third line of defense: the first line is the business units that take and manage risk, the second is risk and compliance functions that set policy and oversee, and the third is internal audit, which independently and objectively reviews all of it.

Internal control. Controls are the checks, approvals, restrictions and reconciliations that keep processes reliable. Auditors test whether they are well designed and whether they operate consistently.

Governance. The IIA explains that internal auditors give executive management and governing bodies assurance that governance processes are sound and internal controls are adequate to mitigate risks. That is why the function reports upward to a board or audit committee. Its value depends on being heard by people who have the authority to act.

Internal audit in security and compliance

For technology and finance organizations, the audit conversation increasingly centers on information security. An internal audit of security might test access reviews, vulnerability management, incident response, vendor due diligence and evidence collected for frameworks such as SOC 2 or ISO 27001.

That work is also where internal audit meets the customer-facing side of the business. Every prospect that sends a security questionnaire is, in effect, asking for a small external audit of your controls. When the answers in those questionnaires disagree with what your internal audit found, you have a trust problem. When they agree, internal audit evidence becomes a sales asset.

If you want to go deeper on the practical side, these guides from our team may help:

• Information security audit process: step-by-step guide walks through scoping, evidence gathering and reporting for security audits.
• Why third-party security reviews matter for risk and compliance explains how vendor reviews connect to your own risk posture.
• SOC 2 auditors and SaaS compliance covers what outside auditors expect from software companies.
• Cybersecurity checklist for enterprises offers a control-by-control starting point for self-assessment.

Our perspective

We talk with security, GRC and sales teams every week, and one pattern is consistent: the same facts about a company's controls get written down several times, by different people, for different audiences. An internal auditor documents them for the audit committee. A compliance manager documents them for a certification. A solutions engineer documents them again for a customer's security questionnaire.

We think that duplication is the real cost, and it is also where accuracy slips. When every answer is typed from memory, two documents describing the same control can quietly disagree.

That is why we built Skypher around a single, maintained knowledge base. Our platform is designed so that approved, versioned content, including the policies and evidence your audit work relies on, becomes the source for questionnaire responses. Our proprietary retrieval AI gives each answer a confidence score, so your reviewers can focus on the few answers that need judgment instead of rereading everything. The result we aim for is that what you tell customers matches what your auditors have verified.

Internal audit asks whether your controls work. We want answering the world about those controls to be fast, consistent and traceable, so your experts spend their time improving controls rather than re-explaining them. Please feel free to reach out if you would like to see how that works in your environment.

Gaspard

Put your audit evidence to work

If your team handles a steady flow of security questionnaires and due diligence requests, our Questionnaire Automation Tool is designed to turn your existing documentation into accurate, reviewable answers across formats, with integrations for the portals and collaboration tools your teams already use. You can also publish your security posture through a customizable Trust Center, so customers find the answers before they ask. To see how it fits your process, visit our site and request a demo.

FAQ

What do internal auditors do?

Internal auditors examine processes, test controls, interview teams, identify risks and inefficiencies, and recommend improvements. They report to senior management and the board or audit committee, then follow up to confirm that agreed actions were completed.

What are the three types of internal audits?

The most common grouping is compliance, financial and operational audits. Longer lists add IT or technology, environmental and performance audits, which overlap with those three. The right type depends on the question the organization needs answered.

What is an example of an internal audit?

A typical example is a review of accounts payable. The auditor samples payments, confirms each had proper approval and a matching purchase order, checks that duties are separated, and reports any gaps with an action plan. A security access review is another common case.

What will be done in an internal audit?

The team plans the scope, gathers evidence through documents, data samples and interviews, compares findings to the criteria, and reports conclusions to management. Management then agrees action plans, and the auditors monitor whether those actions were completed.

Sources

• Definition of Internal Audit, The IIA
• Global Internal Audit Standards 2024, The IIA (PDF)
• 2024 Global Internal Audit Standards, The IIA
• What is internal auditing?, The IIA
• Internal Auditing: assurance, insight and objectivity, The IIA (PDF)
• About internal audit, ICAEW
• A brief guide to internal auditing, ACCA
• Using the Work of Internal Auditors (SAS 128), AICPA (PDF)
• Internal and External Audit Module, FHFA (PDF)
• Internal Audit: Types, Benefits, and Key Elements, Investopedia

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• Information security audit process: step-by-step guide
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• Complete Guide to SOC Type II Reports
• What Is a SOC 1 Report? Definition and Auditor Guide