The study looked at Nigerian companies to see how their internal audit teams affect the fees they pay for external audits. Over four years, they analyzed 60 companies and found that the size and expertise of the internal audit department play a role in determining audit fees. Companies with strong internal audit teams tend to pay more for external audits. However, having a formal internal audit certificate didn't influence the fees paid. In conclusion, companies with well-equipped internal audit departments are likely to spend more on external audit services.