The high rate of merger and acquisition failures indicates that organizations often underestimate the importance of internal audit in mergers and acquisitions. In fact, an international study found that internal auditor participation in strategic planning and specific acquisition planning was only 27 percent and 14 percent, respectively. This gap is concerning, as acquisitions and mergers often fail because insufficient attention is given to conducting organizational audits prior to signing deals.

We've created this guide to help you understand the internal audit role in mergers and acquisitions. We'll cover due diligence strategies, auditing mergers and acquisitions processes, the internal audit role in acquisitions, and mergers and acquisitions internal controls for post-integration success.

The Internal Audit Role in Mergers and Acquisitions: Why Early Involvement Matters

A recent poll revealed that 40% of companies may not be as focused on required internal controls during the M&A life cycle. This gap becomes concerning when you consider that Harvard Business Review estimates 70% to 90% of acquisitions fail. The internal audit function should seek to become involved as early as possible in the M&A process and provide value-added assistance by conducting risk assessments.

Internal audit has evolved from a compliance checkpoint into a trusted advisor that drives organizational success. According to the Institute of Internal Auditors, strategic planning is a requirement under Principle 9 of the Global Internal Audit Standards. During M&A transactions, internal auditors bring independence and objectivity that others on the diligence team may not have.

Without internal audit insight in M&A, costs could range from a loss of opportunity to additional investments required to fix issues that were missed. Furthermore, organizations may not know whether the control environment has sufficient rigor or if risks and controls were taken into account at the time of valuation. Internal auditors can assess the makeup of the current control structure from a risk viewpoint, identifying issues such as disproportionately high numbers of manual controls compared to automated controls. We can also review results from internal and external audits to determine current issues at the organization.

Auditing Mergers and Acquisitions: The Due Diligence Phase

Due diligence serves as the safety net that can save buyers from costly mistakes. An estimated 70-75% of M&A fail due to factors like poor due diligence, inadequate integration planning, and lack of strategic alignment. During this phase, auditing mergers and acquisitions requires systematic examination across multiple risk domains.

Compliance Officers bear considerable responsibility for ensuring regulatory due diligence reviews identify potential legal violations, corrupt arrangements, data privacy issues, and improper billing practices. We assess the target's governance, risk, and controls environment to determine how the company operates and how financial data flows into key reports. This includes reviewing results from internal and external audits to understand current deficiencies and what compensating controls exist.

Financial books require thorough analysis, examining statements, tax returns, and supporting ledgers for consistency and possible misstatements. Equally important is contract review, particularly examining all active agreements for loopholes, dispute histories, or undisclosed side agreements. Third-party risk management at the acquisition target needs evaluation to determine if vendor risks are properly identified and systematically managed.

Technology due diligence has evolved into a critical component of M&A analysis. We examine IT infrastructure, cybersecurity posture, technical debt, and integration complexity. Internal controls assessment provides valuable insights into operational efficiency, financial integrity, and regulatory compliance status.

Connecticut Perspective: Hartford and Fairfield County

In Connecticut, especially across Hartford, Greenwich, Westport, New Haven, and Fairfield County, middle-market acquisitions often combine founder-led businesses with different systems, accounting policies, and compliance practices. Internal audit becomes critical when buyers need clean financial reporting, reliable inventory or service metrics, and fast control alignment across locations before synergy targets slip.

Mergers and Acquisitions Internal Controls: Post-Integration Success Strategies

Once the deal closes, mergers and acquisitions internal controls become the foundation for realizing anticipated synergies. Research shows that 70% of mergers fail due to poor post-merger integration, making the internal audit role in acquisitions critical during this phase. We establish an Integration Management Office to oversee coordination between functional work streams and maintain accountability throughout the process.

Day One readiness demands our immediate attention across three core areas: communications, operative structure, and systems. The First 100 Days represent a high-visibility window where we set the critical path toward value realization. During this period, we harmonize policies and consolidate documentation to create a single source of truth for the newly combined organization.

Cultural integration presents one of the most persistent challenges in auditing mergers and acquisitions. We conduct cultural assessments through surveys, focus groups, and leadership interviews to identify potential fault lines that could derail progress. Similarly, we align cybersecurity frameworks by harmonizing policies, revalidating user permissions, and deploying advanced threat detection during integration.

Compliance monitoring requires continuous oversight. We review internal controls post-acquisition to provide a clearer picture of potential risks while standardizing procedures across both entities. Furthermore, we update privacy policies and data security practices to reflect the merged company's posture, ensuring regulatory compliance as systems integrate and workflows evolve.

Conclusion

Internal audit participation in M&A can mean the difference between a successful integration and becoming part of the 70-90% failure statistic. Without a doubt, early involvement matters most. We've outlined the framework you need to assess risks during due diligence and maintain control through post-integration. Your next acquisition deserves the rigor and objectivity that internal audit brings. Start involving your audit team from day one, and you'll significantly improve your chances of realizing the synergies you're counting on.

Frequently Asked Questions

What is the role of internal audit in a merger or acquisition?

Internal audit checks whether the target company’s controls, reporting, compliance, and operational processes are ready for ownership change. It helps identify gaps before they become expensive post-close problems and gives the buyer a practical remediation roadmap.

When should internal audit be involved in M&A?

Internal audit should be involved as early as diligence and planning allow, ideally before signing or immediately after exclusivity. Early involvement helps the deal team assess control risks, confirm integration assumptions, and avoid surprises in the first 100 days.

What risks does internal audit look for after an acquisition?

Common post-close risks include weak financial controls, duplicate vendors, inconsistent policies, access-management failures, tax exposure, cybersecurity gaps, and inaccurate reporting. Internal audit prioritizes the highest-impact issues and tracks remediation until controls stabilize.

Is internal audit the same as due diligence?

No. Due diligence evaluates the target before closing to inform price and structure, while internal audit focuses on controls, testing, and remediation across the transaction lifecycle. The two functions overlap, but internal audit is broader and more operationally focused.

If you’re planning a business acquisition in Hartford Central or anywhere in Connecticut, request a free consultation or valuation review. We’ll help you pressure-test integration risks, improve deal readiness, and protect value before and after closing.