Non-audit Services and Audit Quality of Listed Industrial Goods Manufacturing Companies in Nigeria

As audit firms expand into non-audit services (NAS), concerns about compromised audit quality have intensified - especially in emerging markets like Nigeria, where regulatory frameworks are still maturing. While NAS can boost efficiency and decision-making, they raise critical issues regarding auditor independence. This study investigates the impact of NAS on audit quality among listed industrial goods manufacturing companies in Nigeria. A quantitative, survey-based approach was adopted, targeting 181 accountants and auditors across 13 NGX-listed firms. Using stratified, purposive, and convenience sampling, 138 respondents were selected via Slovin’s formula. Data were collected through a validated and reliable questionnaire (Cronbach’s alpha > 0.7) and analyzed using descriptive and multiple regression techniques at a 5% significance level. Findings reveal that NAS significantly affect auditor experience (Adjusted R² = 0.222; F = 6.283; p < 0.05) and auditor reputation (Adjusted R² = 0.134; F = 10.769; p < 0.05), both proxies for audit quality. The study concludes that NAS have both positive and negative implications for audit quality. These results highlight the need for clearer regulatory boundaries, stronger oversight, and improved governance to manage NAS in Nigeria’s industrial goods sector. The study provides valuable empirical evidence for regulators, audit committees, and policymakers seeking to safeguard audit quality without stifling professional service innovation.