A standard audit and assurance engagement isn't a one-size-fits-all service—what your business receives depends on scope, industry, and regulatory requirements. Understanding what's actually included helps you budget accurately, set realistic timelines, and know whether you're getting comprehensive coverage or a stripped-down review.
The Core Components of an Audit Engagement
An audit engagement typically includes planning, fieldwork, testing, and reporting across these foundation areas:
Planning and Risk Assessment
Your auditor begins by understanding your business, industry risks, and financial reporting environment. They'll assess materiality levels (the threshold above which errors matter), identify high-risk areas, and design an audit approach tailored to your operations. This phase usually takes 1–3 weeks and sets the tone for everything that follows.
Internal Controls Evaluation
Auditors test whether your financial controls actually work. This means examining how transactions are authorized, recorded, and reconciled—everything from purchase approvals to bank reconciliations. They're looking for gaps that could allow errors or fraud to slip through undetected.
Substantive Testing of Transactions and Balances
This is the hands-on verification. Auditors trace transactions through your books, confirm balances with external parties (banks, suppliers, customers), and test journal entries for accuracy. They'll typically sample transactions rather than testing every single one, using statistical methods to determine appropriate sample sizes.
Financial Statement Review
Your auditor reviews the complete set of financial statements (balance sheet, income statement, cash flow statement, and notes) for accuracy, completeness, and compliance with accounting standards like GAAP or IFRS.
What You'll Receive as Deliverables
The Audit Report
This is your primary output—typically an unqualified opinion (clean bill of health), qualified opinion (minor issues noted), or adverse opinion (significant problems). Standard reports run 1–3 pages and state whether your financial statements present a fair view of your financial position.
Management Letter
Beyond the formal report, auditors provide a management letter identifying control weaknesses, compliance observations, and recommendations for improvement. This document often contains the most actionable insights for your finance team.
Audit Working Papers
You'll have access to the detailed documentation supporting the audit conclusion—test results, confirmations, reconciliations, and analysis. These protect both you and the auditor if questions arise later.
Draft and Final Financial Statements
If included in your engagement, auditors will help finalize your financial statements with any necessary adjustments identified during testing.
Key Variables That Affect Scope
Regulatory Requirements
Public companies, nonprofits receiving federal grants, and financial institutions face mandated audits with specific scope requirements. If you're a private company, you might choose a voluntary audit for loan requirements or investor confidence.
Company Size and Complexity
A $5 million manufacturing business requires deeper inventory and fixed-asset testing than a $5 million service firm. Multiple locations, foreign operations, or complex transactions expand scope significantly.
Industry-Specific Standards
Healthcare providers, credit unions, and insurance companies often need audits following specialized standards (HHS, NCUA, NAIC). These add testing layers not required for general companies.
Engagement Letter Scope
Your auditor specifies exactly what's covered. Some engagements exclude certain account balances, subsidiaries, or locations to reduce cost. Be clear on what's in and out before signing.
Timeline and Effort Expectations
A typical audit for a mid-sized private company takes 4–8 weeks from start to finish, though complex organizations can stretch to 12+ weeks. Expect:
- Planning and fieldwork kickoff: Week 1–2
- Interim fieldwork (testing controls and transactions): Week 3–4
- Year-end fieldwork (final balances and adjustments): Week 5–7
- Report drafting and review: Week 8
Your finance team will need to dedicate 20–40 hours gathering documents, preparing schedules, and answering auditor questions.
Cost Considerations
Standard audit fees typically range from $10,000–$50,000+ depending on size, complexity, and location. International audits, specialized industries, or companies with multiple locations can exceed $100,000. Some firms charge hourly rates ($200–$400+ per hour) rather than fixed fees. If you're comparing providers, Mercoly lets you request and compare quotes from trusted audit and assurance firms in one place, making it easier to evaluate both scope and pricing.
Frequently Asked Questions
Q: Do I need a full audit or would a review engagement work instead? A: Reviews cost 40–60% less but provide less assurance—they're suitable for internal decision-making or smaller loan requirements, while audits are required for public companies, government contracts, and major lending arrangements.
Q: What happens if the auditor finds a material error during the engagement? A: Your auditor will discuss the error with management, determine whether it needs correction in the financial statements, and note it in the audit report or management letter depending on significance and resolution.
Q: Can I use last year's audit report to satisfy current stakeholder requirements? A: No—audits are specific to the fiscal year examined, and most lenders, regulators, and investors require current-year reports (typically within 120 days of year-end).
Start comparing audit and assurance providers today to find the right fit for your business.