A public company audit and a private company audit share a central purpose: providing independent, reasonable assurance that financial statements are free from material misstatement. Yet the standards, oversight, independence rules, and reporting responsibilities can differ considerably. For a company preparing for an IPO, selecting an auditor without understanding those differences may lead to additional procedures, higher costs, and delayed filings.

In the United States, audits of SEC issuers generally follow Public Company Accounting Oversight Board (PCAOB) standards. Many nonissuer private company audits instead follow standards established by the American Institute of Certified Public Accountants (AICPA) Auditing Standards Board. This guide explains the differences, the public company audit requirements to evaluate, and what to look for in a qualified audit firm.

What Is a Public Company Audit?

A public company audit is an independent audit of financial statements performed under the standards applicable to an SEC issuer. In a typical U.S. issuer engagement, an independent PCAOB-registered accounting firm audits the statements and issues an opinion under applicable PCAOB standards.

Who needs a PCAOB audit?

· Companies filing audited financial statements in SEC annual reports

· Businesses preparing a traditional IPO registration statement

· SPACs and certain De-SPAC transaction participants

· Other issuers subject to relevant SEC and PCAOB requirements

The precise requirements depend on the issuer and transaction. Read MBP Global’s PCAOB Audit Guide for more context.

What does the auditor examine?

The audit generally includes risk assessment, evaluating significant accounting policies and estimates, testing transactions and disclosures, obtaining sufficient appropriate evidence, and reporting findings. Certain issuers also require an independent opinion on internal control over financial reporting (ICFR).

What Is a Private Company Audit?

A private company audit examines financial statements for a nonissuer, usually under AICPA U.S. generally accepted auditing standards (GAAS). It may be requested by lenders, owners, investors, regulators, or prospective acquirers even when the company has no SEC annual filing obligation.

Reasons private companies commission audits

· Bank loan covenants and financing agreements

· Investor or ownership arrangements

· Mergers, acquisitions, or capital raising

· Contractual, statutory, or governance obligations

Private audits also require professional skepticism, risk-based procedures, evidence, and an independent opinion. They are not automatically less rigorous or less reliable. MBP Global’s Financial Statement Audit Guide explains what management can expect during an audit.

Public Company Audit vs Private Company Audit: Key Differences

PCAOB vs AICPA Standards: What Actually Changes?

PCAOB audit framework

The PCAOB establishes standards for audit planning, supervision, evidence, estimates, auditor reporting, audit committee communications, and other areas. Registered firms are subject to PCAOB oversight. Audit-period effective dates matter; the engagement team should apply the standards effective for the period being audited.

AICPA auditing framework

The AICPA Auditing Standards Board issues Statements on Auditing Standards, codified in AU-C sections. These cover risk assessment, fraud, documentation, materiality, audit evidence, going concern, and auditor reports. They generally apply to nonissuer financial statement audits.

Does one framework offer stronger assurance?

Both frameworks seek reasonable, not absolute, assurance. Neither guarantees discovery of every fraud or error. The practical distinction is the set of professional requirements and oversight applicable to a specific engagement, rather than a simple “better versus worse” comparison.

Public Company Audit Requirements Under SEC Rules

PCAOB-registered and independent auditor

SEC issuer audits generally require a PCAOB-registered firm that meets applicable independence requirements. Independence restrictions may prohibit certain bookkeeping, valuation, internal audit outsourcing, and management services. Explore MBP Global’s SEC Auditor Independence Rules article for related considerations.

Annual and quarterly financial reporting

Domestic reporting companies generally file audited annual financial statements in Form 10-K and quarterly financial information in Form 10-Q, typically subject to independent review rather than a full quarterly audit. Learn more in SEC Audit Requirements for Public Companies.

SOX and internal control reporting

SOX Section 404(a) involves management reporting on ICFR when applicable; Section 404(b) auditor attestation applies to certain issuers. Qualifying emerging growth companies and non-accelerated filers are generally exempt from 404(b). Additional transition rules may apply. The SOX Compliance Checklist offers practical preparation points.

Audit committee responsibilities

Listed issuers generally have audit committee responsibilities involving independent auditor oversight, appointment, compensation, and permitted non-audit services. Management still owns the financial statements and internal controls.

How Do Public and Private Company Audit Reports Differ?

Public company audit reports and critical audit matters

PCAOB reports include the opinion and basis for opinion, and for relevant issuers, disclosures of critical audit matters (CAMs). CAMs concern matters communicated or required to be communicated to the audit committee, related to material accounts or disclosures, that involved especially challenging, subjective, or complex auditor judgment. CAM reporting exemptions apply to certain issuer categories.

Private company audit reports

AICPA audit reports generally present the auditor’s opinion, basis for opinion, and management and auditor responsibilities. Depending on circumstances, both frameworks can result in a qualified or adverse opinion, or a disclaimer of opinion. Specific reporting language and requirements differ.

Can a Private Company Use an AICPA Audit for an IPO?

An audit performed solely under AICPA standards generally does not satisfy applicable PCAOB auditing requirements for issuer financial statements included in an SEC registration statement. A company planning an IPO should evaluate the standards used for prior financial statements, its auditor’s registration and independence, and which historical periods will be filed.

Questions to resolve early

·  Is the current auditor registered with the PCAOB?

·  Are all required periods covered under the appropriate audit standards?

·  Do earlier services create any independence conflict?

·  Are financial statements and disclosures suitable for the intended SEC filing?

·  Is there enough time for additional procedures or a new engagement?

The Pre-IPO Auditor Selection Guide explains practical criteria for evaluating firms before the filing timetable becomes urgent.

Are Public Company Audits More Expensive?

They can be, but cost is driven by engagement scope, complexity, the company’s controls, multiple locations or subsidiaries, reporting periods, required ICFR work, and specialist accounting issues. A highly complex private company audit may cost more than a relatively straightforward public company engagement.

What should an audit proposal cover?

·  Applicable standards and financial statement periods

·  Included entities, locations, and required deliverables

·  Partner and engagement team responsibilities

· Assumptions about accounting records and audit readiness

·  Estimated timetable, fees, and change-of-scope terms

Evaluate the substance of the proposed engagement, not the fee alone. To discuss fit for a specific company, review MBP Global’s Audit & Assurance Services.

How to Choose the Right Audit Firm

Confirm qualifications and independence

Verify PCAOB registration where applicable and ask the firm to evaluate independence for all relevant periods. Request examples of comparable issuer or nonissuer engagements.

Assess technical and industry experience

Consider relevant expertise in revenue recognition, financial instruments, acquisitions, equity compensation, consolidated reporting, and the industry’s common risks.

Evaluate staffing and communication

Identify the engagement partner, escalation process for complex accounting questions, expected deliverables, and realistic capacity to meet deadlines.

Consider your future reporting needs

A private business preparing for U.S. capital markets should consider whether a proposed firm can support both today’s audit and anticipated regulatory needs.

Public Company Audit Readiness Checklist

·   Determine whether SEC/PCAOB standards apply to the intended filing

·   Identify audited periods and relevant legal entities

·   Verify the auditor’s qualifications and independence

·   Complete significant account reconciliations

·   Document complex transactions and accounting estimates

·   Review required disclosures and internal controls

·   Determine whether SOX 404(b) applies

·  Confirm audit committee communication processes

· Build a realistic audit and filing calendar

·  Plan for future quarterly review and annual audit obligations

How MBP Global LLP Supports Public and Private Company Audits

MBP Global LLP provides audit and assurance services for public and private companies, including SEC/PCAOB audits, private company audits, IPO-related engagements, and relevant financial statement reviews. Its partner-led approach can be valuable when companies need specialized experience and clear communication about reporting obligations.

A firm cannot take over management’s financial reporting responsibilities or guarantee that a company will satisfy every SEC obligation. The right engagement can, however, support reliable audit evidence and appropriate independent assurance.

Explore Audit & Assurance Services or Contact MBP Global LLP to discuss which audit standards and engagement scope apply to your business.

Frequently Asked Questions

What is the main difference between public and private company audits?

U.S. issuer audits generally use PCAOB standards and SEC-related requirements; nonissuer audits commonly follow AICPA U.S. GAAS.

What standards govern a public company audit?

PCAOB auditing standards generally apply to SEC issuer financial statement audits, together with relevant independence and reporting requirements.

Do private companies need PCAOB audits?

Most do not solely because they are privately held, but an anticipated IPO or another specific regulatory transaction can change the required framework.

Can a PCAOB-registered firm perform an AICPA audit?

Yes. The firm can perform an engagement under applicable AICPA standards, but PCAOB registration does not automatically turn that audit into a PCAOB audit.

Does every public company need an ICFR audit?

No. SOX 404(b) applies to certain issuers; qualifying emerging growth companies and non-accelerated filers are generally exempt.

Can a private company audit be converted for IPO use?

Not through an administrative change alone. Additional procedures or a new engagement may be necessary, depending on the history and circumstances.

How should we select an IPO auditor?

Assess independence, PCAOB registration, relevant SEC experience, technical expertise, staffing, communication, and realistic timelines.

What drives public company audit costs?

Size, complexity, risks, entities, control environment, financial statement periods, and any required integrated audit work are major factors.

Conclusion: Match the Audit Standard to the Business

Both PCAOB and AICPA audits provide reasonable assurance, but the correct standards and auditor qualifications depend on the entity and intended financial reporting use. For businesses considering an IPO or other U.S. public market transaction, addressing the distinction early can help avoid preventable delays and rework.

For an engagement-specific discussion, visit MBP Global’s Audit & Assurance Services or Contact MBP Global LLP