Critical Mistakes Companies Make When Building an Internal Control System

At some point during growth, most companies run into the need for an internal control system: approval mechanisms become dependent on specific individuals, processes go undocumented, and risk points are no longer visible. Yet a significant share of internal control initiatives never deliver the expected benefit, undone by a handful of recurring mistakes, and over time they turn into structures that exist on paper but do not function in practice. In this article, we examine the mistakes most frequently encountered in the field and how they can be avoided.

Mistake 1: Designing the Control Checklist in Isolation from the Process

The most common mistake is building the internal control system as a generic, one-size-fits-all checklist detached from actual business processes. Trying to apply a standard template downloaded from the internet produces a structure that looks complete on paper but does not operate in reality. Unless control points are embedded organically into the daily workflow of process owners, they will be bypassed during the first busy period and eventually forgotten.

Why This Matters

Controls disconnected from the process are perceived by employees as "bureaucratic overhead" and skipped at the first opportunity. An effective internal control system must be a natural part of the process steps rather than a separate formality. The way to achieve this is to design controls together with process owners, based on the workflow as it actually happens on the ground.

Mistake 2: Adding Controls Without Prioritizing Risk

When some companies recognize a control gap, they react by adding numerous new approval steps. But applying controls of equal weight to every process reduces operational efficiency while allowing the genuinely critical risks to fade into the background. In a risk-based approach, control intensity should be proportionate to the magnitude and likelihood of the risk; not every transaction warrants the same level of scrutiny.

• Processes with high financial impact (supplier payments, cash management, contract approvals, for example) should be subject to tighter controls
• For low-risk, repetitive transactions, the level of control should stay proportionate and light
• Risk assessment should be updated periodically rather than treated as a one-time exercise
• The balance between the cost of a control and the risk it mitigates should be reviewed continuously

Mistake 3: Not Using an Established Framework

Internal control structures designed around in-house rules, aligned with no recognized reference framework, create credibility problems with auditors and investors alike. The COSO framework offers a structure tested internationally over many years, built on five components: control environment, risk assessment, control activities, information and communication, and monitoring. Anchoring the system to this framework ensures alignment with both corporate and audit standards and builds confidence among external stakeholders.

A Practical Checklist

When assessing your internal control system against COSO, you should be able to answer the following questions clearly:

• Control environment: Has management clearly defined a culture of ethics and accountability?
• Risk assessment: Is the company's risk universe current, documented, and reviewed on a regular basis?
• Control activities: Are approval, segregation of duties, and reconciliation steps embedded in the processes?
• Information and communication: Do control results reach the right people, at the right time, in a form they can act on?
• Monitoring: Is the effectiveness of controls tested independently at regular intervals?

Mistake 4: Leaving the System Static After Implementation

An internal control system is not a document to be set up once and shelved. As the company grows, enters new markets, acquires a subsidiary, or changes its organizational structure, its risk profile changes too. Failing to review the control matrix periodically causes the system to drift away from reality over time, with control points aimed at risks that no longer apply.

An effective internal control system is worth only as much as the regularity with which it is tested and updated, not merely the effort that went into building it.

For this reason, the internal control system should be reviewed at least once a year, and separately after any significant organizational change. A control system without a follow-up mechanism quickly becomes a formality.

Mistake 5: Treating Compliance Reporting as a Formality

Compliance reporting is not simply about producing a document for the board or the audit committee; it is a feedback mechanism that allows control weaknesses to be identified and corrected early. When the reporting process becomes a box-ticking exercise, the system drifts from its purpose and real risks go unnoticed. Effective reporting should rest on measurable indicators (KPIs) and feed directly into management decision-making.

Mistake 6: Neglecting Segregation of Duties

Concentrating the initiation, approval, and recording of a transaction in a single person is one of the most common weaknesses in internal control systems. In small and medium-sized companies, resource constraints often mean this separation is overlooked; but as the company grows, it increases both the risk of error and the likelihood of fraud. Segregation of duties can largely be achieved without hiring additional staff, simply by reorganizing how responsibilities are distributed within the existing team.

An Actionable Roadmap

In critical processes (procurement, payment approval, and inventory receipt, for example), make sure at least two people are involved, and identify, prioritize, and remediate the points where a single person holds end-to-end authority. This is one of the steps in an internal control system that delivers the fastest improvement at the lowest cost.

How to Begin Building an Internal Control System

For companies looking to build an internal control system from scratch, the recommended approach is to start from a narrow but concrete starting point rather than a broad, long-running project. The steps below outline a sequence that works in practice:

• Identify the two or three processes that carry the highest financial or operational risk, and focus on those first
• Map the current workflow step by step together with process owners, observing control points in the field
• Prioritize the gaps you identify by risk magnitude rather than trying to close them all at once
• Document the control procedures and communicate them to the relevant teams, reaching the people who apply them and not just management
• Test at set intervals (quarterly, for example) whether the controls are actually being applied

Once these steps are complete, the scope can be expanded gradually to cover other processes. A small, manageable start delivers far more durable results than an ambitious project left unfinished.

Building an Internal Control System the Right Way

What these mistakes share is treating the internal control system as an isolated, reactive, and static exercise. A sound implementation depends on analyzing processes in the field, prioritizing risks, grounding the design in an established framework such as COSO, and keeping it alive through regular follow-up. This is not a one-time project but a continuous part of corporate governance, and it should be addressed in an integrated way alongside the company's other finance and tax processes. Otherwise, the control system soon becomes a document that no one owns and no one updates, and it fails to deliver the assurance expected of it at the first sign of crisis.

Ultimately, the real question facing a company that wants to build an internal control system is not "which template should we use" but "which of our risks are truly critical, and who will control them in the field, how, and how often." A system that answers these questions clearly becomes more than a way to pass an audit: it becomes a lasting management tool that adds value to day-to-day operations.

If you would like to assess which of these six mistakes your company's internal control system may be exposed to, explore MerSar's Internal Control and Audit service and request a free initial consultation so we can review your current structure together.