Due diligence checklist: buy a business step by step

Published Tuesday 21 April 2026

Table of contents

• What is due diligence when buying a business?
• Why is due diligence important?
• How long does due diligence take?
• How to conduct due diligence step-by-step
• Essential due diligence checklists before buying a business
• Key documents to review during due diligence
• FAQs on due diligence when buying a business

Key takeaways

• Assemble a team of professionals — including an accountant, lawyer, and business broker — before you start reviewing documents, as they can identify financial and legal risks you might miss on your own.
• Review at least three to five years of tax returns, financial statements, and cash flow records to verify the seller's claims and confirm the business can generate the returns you expect.
• Investigate five key areas during due diligence — finances, legal standing, operations, market position, and regulatory compliance — to get a complete picture of what you're buying.
• Renegotiate the purchase price, request the seller resolves issues, or walk away entirely if due diligence uncovers problems that make the deal too risky.

What is due diligence when buying a business?

Due diligence is how you systematically investigate a business before you buy it. It verifies the business's financial health, legal standing, and growth potential so you can decide whether to purchase.

Incoming directors have a legal duty of care and diligence under the Corporations Act, making thorough due diligence essential.

Why is due diligence important?

Due diligence protects your investment by uncovering hidden risks before you commit to buying a business. The seller represents their business, but verifying those claims is your responsibility.

Proper due diligence helps you:

• Pay fair value: avoid overpaying for inflated or misrepresented assets
• Identify risks: spot potential problems before they become your problems
• Ensure compliance: meet legal and regulatory requirements

Skipping due diligence can expose you to:

• Financial risks: hidden liabilities, overstated earnings, or unreported debts
• Tax exposure: unresolved tax implications or unreliable revenue sources
• Legal consequences: regulatory non-compliance that may result in fines or business closure
• Operational weaknesses: outdated systems, inefficiencies, or fragile supplier relationships
• Market vulnerabilities: hidden reputational issues or competitive weaknesses

Get expert advice for your due diligence checklist, especially for legal and financial matters.

How long does due diligence take?

Due diligence typically takes four–12 weeks, depending on business size and complexity. A small business may require only a few weeks, while larger or more complex acquisitions can take several months.

Key factors that influence the timeline include:

• Business size: larger businesses require more documents and verification
• Operational complexity: multiple locations, products, or services add review time
• Seller responsiveness: how quickly the seller provides necessary documents

Don't rush. Being thorough helps you make a confident, informed decision.

How to conduct due diligence step-by-step

Due diligence follows a structured process that moves from preparation through to final decision. Here's how to work through it systematically.

1. Assemble your team: Engage an accountant, lawyer, and business broker before you start reviewing documents.
2. Request financial documents: Ask the seller for three to five years of tax returns, financial statements, and profit and loss records.
3. Review legal standing: Have your lawyer check contracts, licences, intellectual property, and any past or pending litigation.
4. Assess operations: Evaluate management structures, staffing, supplier relationships, and technology systems.
5. Analyse market position: Research competitors, customer concentration, and growth potential.
6. Identify red flags: Document any inconsistencies, undisclosed liabilities, or seller reluctance.
7. Compile your findings: Summarise risks and opportunities to inform your final decision.
8. Make your decision: Negotiate based on findings, request remediation, or walk away if risks are too high.

Each step builds on the previous one. Don't skip ahead or make commitments until you've completed the full review.

Essential due diligence checklists before buying a business

A due diligence checklist ensures you investigate every critical aspect of the business systematically. These five categories cover the essential areas that determine whether a business is worth buying:

• Financial due diligence
• Legal due diligence
• Operational due diligence
• Market position and competitive analysis
• Regulatory and compliance

Work with professionals throughout. Ask your accountant to review the finances and your lawyer to check legal documents and contracts.

The following sections break down each category in detail.

Financial due diligence

Financial due diligence verifies the business's profitability, cash flow, and financial stability. Analysing these areas reveals whether the business can sustain operations and generate the returns you expect.

Check these key financial areas:

• Review three to five years of tax returns, financial statements, and profit and loss records
• Check current tax status and identify outstanding liabilities
• Check for hidden debts, loans, and financial obligations
• Analyse current cash flow patterns and growth potential
• Compare revenue trends against industry conditions and forecasts where available

If accounting is incomplete at the time of purchase, you have up to one year from the acquisition date to complete the post-acquisition measurement period.

Legal due diligence

Legal due diligence checks the business's legal standing, including any current or past legal issues.

Review these legal areas:

• Review all contracts and licences, including supply, customer, operational, and employee agreements
• Check for intellectual property rights, including patents, trademarks, copyrights, and trade secrets
• Verify business name registration, domain registration, and trademark ownership
• Investigate past or pending litigation, lawsuits, or other legal disputes

Your accountant must comply with APES 110 section 260 when responding to non-compliance with laws and regulations.

Operational due diligence

Operational due diligence checks how the business runs day to day. It reveals whether systems, processes, and relationships will support continued success.

Review these operational areas:

• Review business plans and strategy documents
• Evaluate operations, management structures, and staffing arrangements
• Assess customer and supplier relationships and contracts
• Review business assets and equipment, including age and maintenance schedules
• Check technology infrastructure, data security, and software systems for scalability

Market position and competitive analysis

Market position analysis determines the business's competitive strength and growth potential. Evaluating these factors helps you assess whether the asking price reflects the business's true market value.

Market due diligence examines:

• Competitive position: how the business compares to direct and indirect competitors
• Customer base: who buys from the business and why they choose it over alternatives
• Market share: the business's portion of the total market and growth trends
• Growth opportunities: potential for expansion and revenue increases

Regulatory and compliance

Regulatory and compliance due diligence checks that the business meets all legal and industry requirements.

Review these compliance areas:

• Review regulatory and compliance obligations for the industry
• Check for issues with licences, permits, premises, or government regulations
• Review tax compliance status, including records, liabilities, and local or international tax laws
• Review compliance with workplace conditions, agreements, and employee entitlements
• Check environmental regulations and potential liabilities in waste management or pollution

Key documents to review during due diligence

Document review provides concrete evidence to support or challenge the seller's claims about the business. These records reveal the true financial performance, legal standing, and operational efficiency.

The documents you need depend on your industry and location. Ask your accountant and lawyer which documents are essential for your specific situation.

Financial and tax

• Tax returns (3–5 years)
• Profit and loss statements (3–5 years)
• Balance sheets (3–5 years)
• Audit reports
• Business credit reports
• Bank loans or other finance
• Leases
• Sales records
• Business valuation(s)

Equipment, assets, and stock

• Plant, equipment, or vehicle leases
• Maintenance records
• Other assets owned or leased
• Outstanding debts to suppliers
• Stock
• Software licences

Legal

• Insurance contracts
• Regulations or compliance issues
• Legal proceedings
• Mandatory codes of practice
• Business standards and procedures
• Legal agreements for directors, partners, or shareholders
• Privacy requirements
• Data management processes

Operations

• Business plans and other strategy documents
• Staff contracts, awards, entitlements, and insurances
• Staff induction and training records
• Licences and permits required to run the business
• Policies and procedures
• Supplier contracts
• Voluntary codes of conduct
• Minutes of management meetings
• Marketing campaign strategy documents
• Branding strategy and guidelines

Intellectual property

• Trademarks
• Patents
• Copyright
• Branding
• Registered designs
• Business registration
• Domain registration

Red flags that should stop a deal

You may find issues that make you reconsider buying. Watch for these common red flags:

• inconsistent financials: financial statements don’t match tax returns or bank records
• undisclosed liabilities: hidden debts or legal claims not mentioned by the seller
• high customer concentration: a large portion of revenue comes from one or two clients (accounting standards include a concentration test to assess this risk)
• poor record-keeping: messy or incomplete documents can hide bigger problems (professional standards require a sufficient and appropriate record of financial procedures)
• reluctance from the seller: the owner is hesitant to provide information or answer questions

You can negotiate some issues, but a major red flag is a sign to walk away.

Do your due diligence right

Thorough due diligence protects you from costly mistakes and gives you confidence in your business purchase decision. The process requires systematic investigation and professional expertise to uncover risks you might miss on your own.

Follow these best practices for effective due diligence:

• Plan for four to 12 weeks depending on business complexity and size
• Don’t make decisions without understanding critical details
• Use professional expertise like your accountant, lawyer and broker to catch issues that could cost more than their fees
• Verify everything and don’t rely only on the seller’s claims, confirm all details with documentation
• You’ll also need financial experts to draft the purchase agreement and guide you through finance and legal technicalities. You can find financial advisors in the advisor directory.
• Make sure you think about the operational and cultural aspects when doing your due diligence. Ideally, the existing culture of the business aligns with your own values, goals, and management style.

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FAQs on due diligence when buying a business

Here are answers to common questions about conducting due diligence when buying a business.

What's the most important part of due diligence?

Financial due diligence is typically the most critical area because it reveals the business's true profitability and sustainability. Review at least three years of tax returns, financial statements, and cash flow records to verify the seller's claims.

Can I do due diligence myself?

You can conduct some preliminary research yourself, but you should always engage professionals for financial and legal due diligence. An accountant and lawyer can identify risks you might miss and ensure you comply with all legal requirements.

How much does due diligence cost?

Due diligence costs vary depending on the business size and complexity. Budget for accountant fees, lawyer fees, and potential specialist consultants. While due diligence has upfront costs, it protects you from far greater losses if problems emerge after purchase.

What happens if due diligence reveals problems?

If you discover issues during due diligence, you have several options. You can renegotiate the purchase price to reflect the risks, request that the seller resolves issues before completion, or walk away from the deal if risks are too high.