What is an audit?

Updated March 2026

Are you wondering what is an audit and how this process can affect your business? Auditing is a recurring subject for directors, partners and financial managers. However, the concept often remains vague: is it a control? A simple accounting audit? A legal obligation?

Here is a direct answer: an audit is an independent and structured mission which consists of examining information, processes or systems in order to assess their reliability, compliance or effectiveness. At the end of his work, the auditor issues a documented conclusion and, where applicable, operational recommendations.

This definition applies to very varied fields. In business, we first think of the financial audit, but there is also the internal audit, the compliance audit, the acquisition audit and even the procedural audit. Each responds to a specific need and follows its own methodology.

In the broad sense, an audit is an examination process which is based on three pillars:

• the independence of the listener in relation to the object examined
• a structured methodology, based on recognized professional standards
• a reasoned conclusion, supported by convincing éléments collected during the work

In France, the référence framework varies depending on the type of audit. The legal audit of accounts is based on the professional standards defined by the High Authority of the Audit Office (H2A). Internal audit follows international standards published by the Institute of Internal Auditors (IIA), relayed in France by IFACI.

The notion of materiality (or significance threshold) is central: an audit does not aim to verify everything, but to identify anomalies or risks likely to influence the recipients' decisions. It is this notion that distinguishes an audit from an exhaustive control.

Hayot Expertise Advice: a good audit is not measured by the quantity of controls carried out, but by the clarity of the link between identified risks, work carried out and useful conclusion for the decision.

An audit always responds to a question of trust. This involves giving a recipient – ​​manager, partner, bank, investor or supervisory authority – reasonable assurance on a given subject.

Concretely, an audit serves to:

• check the reliability of financial, accounting or operational information
• identify risks and significant anomalies
• evaluate conformity in relation to a benchmark (standards, laws, internal procedures)
• formulate recommendations to improve processes and risk management
• strengthen the credibility of the company with its stakeholders

In the economic context of 2026, marked by increasing regulatory complexity and increased requirements in terms of transparency, audit plays a structuring rôle. It is no longer limited to account verification: it now covers tax compliance, the fight against fraud, the cyber security of information systems and even CSR.

The term "audit" covers very différent realities. Here are the main catégories you will encounter.

Legal audit and auditors#

The legal audit is an account certification mission, entrusted to an auditor (CAC). It is mandatory for certain companies exceeding thresholds defined by the Commercial Code (turnover, balance sheet total, workforce).

The CAC examines the annual accounts and certifies, with reservation or with refusal if necessary, that they are regular, sincere and give a faithful image of the assets and financial situation of the company. Its standards of practice are set by the H2A, the supervisory authority of the profession.

To learn more about the threshold criteria and the issues specific to SMEs, consult our article on the SME financial audit zoom.

Contractual audit#

The contractual audit is a mission carried out at the request of a manager, a partner or a third party, without legal obligation. It can relate to a specific scope: audit of a target's accounts with a view to an acquisition, analysis of a specific balance sheet item, review of internal procedures.

Its strength lies in its flexibility: the scope, depth of the work and the format of the report are adapted to the needs of the sponsor.

Internal audit#

Internal audit is an independent and objective activity which gives an organization assurance on the degree of control of its operations, provides advice to improve them, and contributes to creating added value. This definition, set by IFACI, underlines the continuous and improving nature of the approach.

Unlike the auditor, the internal auditor does not certify the accounts. It evaluates the effectiveness of internal control, risk management and governance. Its recommendations aim to strengthen operational performance.

Discover the rôle in detail in our internal auditor zoom.

Acquisition audit#

The acquisition audit (or due diligence) supports external growth operations. It examines the financial, tax, social and legal situation of a target before finalizing a transaction. The objective: identify hidden risks, adjust the transfer price or negotiate liability guarantees.

Whatever its nature, an audit generally follows a methodological séquence in four phases:

1. Awareness and planning — the auditor understands the entity's environment, identifies risk areas and defines the work program.
2. Execution of work — conformity tests, substantive tests, analytical analyses, interviews, surveys. The auditor collects evidence to support his conclusion.
3. Évaluation of anomalies — the identified deviations are analyzed with regard to materiality. The auditor distinguishes significant anomalies from minor irregularities.
4. Report and recommendations — the conclusion is formalized in a report. In legal audit, this involves the certification of accounts. In contractual or internal audit, the report includes actionable recommendations.

To understand how the auditor assesses the reliability of financial information, visit our article on audit assertions.

It is essential to understand what an audit is not:

• This is not a guarantee of complete absence of error. The audit provides reasonable, not absolute, assurance. Certain risks, notably elaborate fraud, may escape the procedures.
• It is not a substitute for daily management. The auditor does not run the company. Responsibility for preparing accounts and internal control rests with managers.
• This is not a simple documentary formality. A serious audit is based on professional judgment, target surveys and critical analysis — not on an administrative checklist.

These limits do not call into question the usefulness of the audit. They simply invite us to expect what it can really provide: documented assurance and concrete avenues for improvement.

Confusion is common. The accountant assists the manager in bookkeeping, drawing up accounts and providing management advice. He is involved in the production of financial information. The auditor (auditor) examines and certifies this same information in complete independence. The two missions are complementary but incompatible on the same scope: an accountant cannot certify the accounts that he himself has prepared.

In 2026, a well-thought-out audit is much more than an obligation or a formality. It is a tool for reliability, prioritization and credibility in the service of decision-making. Its true value appears when its conclusions are taken seriously and translated into concrete actions. Whether you are a manager faced with an auditing obligation, a partner wishing to make your company's financial information more reliable, or an investor evaluating a target, understanding what is an audit is the first step to getting the most out of it.

Do you want to frame a useful and actionable audit?
We help you define the right scope, the right level of analysis and the concrete follow-ups to be given.

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(Sources: économie.gouv.fr, H2A, IFACI)