Cost of debt for private firms revisitedIchev, Riste (Avtor) Koren, Jernej (Avtor) Kosi, Urška (Avtor) Sitar Šuštar, Katarina (Avtor) Valentinčič, Aljoša (Avtor) private companyinternal auditingindebtednessriskrisk managementprivate firmsvoluntary auditcost of debtself-selection biasWe examine the relation between voluntary audit and the cost of debt in private firms. We use a sample of 7,420 small private firms operating in the period 2006-2022 that are not subject to mandatory audits. Firms self-select into voluntary audits because of the economic setting (e.g., ownership complexity, export, subsidiary status) or because firm fundamentals limit their access to financial debt. In the outcome analyses, we find that voluntary audits result in higher, rather than lower, interest rates with increases ranging from approximately 1.7 percentage points, but going higher depending on the exact specification. This effect is present regardless of the perceived audit quality (Big-4 vs. non-Big-4), consistent across auditor types. Audited firms’ earnings are less informative about future operating performance. Voluntary audits facilitate access to financial debt for high-risk firms. The price paid is reflected in higher interest rates for voluntary audits – firms with higher information/fundamental risk.20262026-07-06 16:28:49Članek v reviji184415UDK: 005.336.1ISSN pri članku: 1059-0560DOI: 10.1016/j.iref.2026.105474COBISS_ID: 280069379sl