Internal Audit Switzerland: Requirements (2026)

Swiss law distinguishes between the statutory external audit (required by the Code of Obligations for most companies) and internal audit (an optional but recommended governance function for larger organisations). This guide covers both: who must have an external audit in Switzerland, when internal audit becomes important, and how Swiss audit requirements scale with company size.

External Audit: Swiss Law Requirements

Ordinary Audit (Ordentliche Revision)

An ordinary audit (conducted by a licensed audit firm) is mandatory for companies that exceed two of the three following thresholds in two consecutive financial years:

Additionally, ordinary audit is always required for:

• Listed companies (shares traded on SIX or regulated market)
• Companies obligated to consolidate (parent companies of groups)
• Companies that issue bonds publicly

What ordinary audit involves: The auditor issues an opinion on whether the financial statements present a true and fair view in accordance with Swiss GAAP, OR (if applicable), or IFRS. The auditor must be registered with the Swiss Federal Audit Oversight Authority (RAB — Revisionsaufsichtsbehoerde) as a licensed audit expert (zugelassener Revisionsexperte).

Limited Audit (Eingeschraenkte Revision)

Companies that do not meet the ordinary audit thresholds must conduct a limited audit unless they opt out entirely.

Limited audit characteristics:

• Less thorough than ordinary audit — analytical procedures, enquiries, and targeted testing rather than full substantive testing
• Shorter auditor’s report: negative assurance (nothing came to our attention suggesting the accounts are incorrect) rather than positive opinion
• Auditor qualification: can be a RAB-registered auditor (zugelassener Revisor) rather than a full audit expert

Who qualifies for limited audit: SMEs, GmbH companies, and AG companies below the ordinary audit thresholds.

Audit Opting-Out (Opting-Out)

Small companies can opt out of the audit requirement entirely if:

• The company has fewer than 10 full-time employees on annual average, AND
• All shareholders unanimously agree to waive the audit

Requirements for opting-out:

• All shareholders must consent — a single dissenting shareholder prevents opting-out
• The decision is documented in the shareholder meeting minutes
• Opting-out does not eliminate bookkeeping obligations — annual accounts must still be prepared

Practical note: Banks require audited accounts for lending decisions. Companies seeking financing should consider retaining a limited audit even when legally permitted to opt out.

RAB: The Swiss Audit Oversight Authority

The RAB (Eidgenoessische Revisionsaufsichtsbehoerde) supervises auditors conducting statutory audits of Swiss public-interest entities (PIEs — listed companies, banks, insurance companies).

RAB registration categories:

• Zugelassener Revisionsexperte (licensed audit expert): Required for ordinary audits
• Zugelassener Revisor (licensed auditor): Sufficient for limited audits
• Staatlich beaufsichtigter Revisionsunternehmen: For PIE audit firms — additional oversight by RAB

Auditors who are not registered with RAB cannot conduct statutory audits of Swiss companies.

Major Swiss audit firms:

• Big 4: PricewaterhouseCoopers (PwC), KPMG, Deloitte, Ernst & Young (EY) — all major Swiss PIE auditors
• Mid-tier: BDO, Mazars, Grant Thornton, OBT, Treuhand Suisse network members
• Cantonal and regional fiduciaries: for SME limited audits and opting-out compilations

Internal Audit as a Governance Function

Internal audit (separate from the statutory external audit) is a function within the organisation that provides independent assurance on risk management, controls, and governance.

Swiss law does not mandate internal audit for most companies. However:

For banks and financial institutions: FINMA requires banks to have an independent internal audit function that reports directly to the board of directors. This is a FINMA circular requirement (FINMA Circular 2017/1). For more on FINMA regulatory requirements, see our guide to FINMA licensing in Switzerland.

For listed companies: The SIX Swiss Exchange Corporate Governance Directive recommends internal audit as a best practice, though it is not legally mandatory.

For large corporations: Companies with complex operations, multiple subsidiaries, or significant regulatory exposure typically establish internal audit functions following international standards (IIA — Institute of Internal Auditors standards).

Internal Audit vs External Audit: Key Differences

Audit Requirements for Specific Swiss Entities

For details on forming these entity types, see our guides on AG formation in Switzerland and GmbH formation in Switzerland.

Cost of Swiss Statutory Audit

Limited audit (SME): CHF 3,000-15,000/year depending on company size and complexity

Ordinary audit (mid-size company): CHF 20,000-100,000+/year

Big 4 audit (listed company or bank): CHF 500,000-5,000,000+/year

Frequently Asked Questions

Can the company’s own accountant conduct the statutory audit?

No. Swiss law requires the auditor to be independent from the company — the company’s internal accountant or bookkeeper cannot be the statutory auditor. The auditor must be an external, registered RAB auditor or audit expert.

What happens if a Swiss company does not have a statutory audit?

Failure to conduct the required statutory audit is a violation of Swiss company law. The board of directors can face personal liability. For company registration purposes, the Commercial Register can initiate dissolution proceedings for persistent non-compliance.

Does an audit exemption (opting-out) affect the company’s credibility?

With banks and sophisticated counterparties, opting out of audit can raise questions. Many lenders require a limited audit as a condition of financing, regardless of the legal exemption.

How do I register an auditor with the Commercial Register?

When forming or updating a Swiss company, the appointed auditor must be registered in the Commercial Register alongside the company’s other organs. The auditor must provide proof of RAB registration. If the company opts out of audit, a declaration of opting-out is filed with the Commercial Register instead. For the registration process, see our guide on the commercial register in Switzerland.

Can a foreign audit firm conduct a Swiss statutory audit?

Only audit firms and individuals registered with RAB can perform statutory audits of Swiss companies. Foreign audit firms must establish a Swiss presence and obtain RAB registration. In practice, international audit firms operate through their Swiss member firms (for example, KPMG AG in Switzerland is a separate legal entity from KPMG International).

What is the difference between ordinary and limited audit scope?

An ordinary audit requires full substantive testing — the auditor verifies account balances, samples transactions, and provides a positive opinion on the accuracy of the financial statements. A limited audit uses analytical procedures and enquiries, resulting in a negative assurance statement. The ordinary audit provides significantly greater assurance but costs substantially more.

When does a company need to switch from limited to ordinary audit?

The switch is triggered when the company exceeds two of the three thresholds (CHF 20 million total assets, CHF 40 million revenue, 250 employees) in two consecutive financial years. The company must appoint a RAB-registered audit expert and notify the Commercial Register of the change in auditor status.

Is internal audit mandatory for Swiss holding companies?

No. Swiss law does not require internal audit for holding companies purely on the basis of their holding structure. However, if the holding company is listed, subject to FINMA supervision, or exceeds the ordinary audit thresholds, additional governance expectations apply. Many groups with complex subsidiary structures establish internal audit voluntarily to manage risk across entities.

Can shareholders force a company to retain an audit even if opting-out is available?

Yes. Opting-out requires unanimous shareholder consent. A single shareholder can insist on retaining the limited audit, and the company must comply. This right exists to protect minority shareholders who may depend on audited accounts for oversight of the board’s management.

What are the penalties for an auditor who fails to detect fraud?

Under Swiss law (OR Art. 755), auditors face civil liability for damages caused by negligent or intentional breaches of duty. Shareholders, creditors, and the company itself can bring claims. RAB can also impose administrative sanctions, including revocation of the auditor’s registration. Professional indemnity insurance is mandatory for all RAB-registered audit firms.

Related guides: Company Formation Switzerland | Accounting in Switzerland | Start a Business in Switzerland | Doing Business in Switzerland

Sources: Swiss Code of Obligations (OR) Art. 727-731 on Fedlex | RAB Swiss Federal Audit Oversight Authority | FINMA Audit Requirements