Guzmán Raja, IsidoroRúa Alonso De Corralesc, EnriqueSánchez García, Juan FranciscoGonzález Sánchez, Mariano2024-05-202024-05-2020210210-2412https://doi.org/10.1080/02102412.2021.1919959https://hdl.handle.net/20.500.14468/11910This empirical research uses panel data methodology to find the main factors determining Spanish audit quality. on a sample with more than 60,000 audited companies from 2013 to 2018. Prior to analysing the quality of the audit, we have adjusted the best possible model to the audit fees behaviour in order to extract the abnormal fees. Our dynamic model shows that audited company’s size, the previous year’s audit fees, the years with the same audit firm, the auditor’s opinion, the auditor rotation, the concentration or dedication to the client and the client sector are explanatory factors of audit fees. Further, we find evidence that audit quality improves with number of hours billed for audit work and decreases with sector concentration of auditor and, a novel multiplicative effect, the auditor size by abnormal audit fees, in such a way that the surcharge (abnormal fees) of the big audit firms contribute negatively to improve the audit quality.enAtribución-NoComercial-SinDerivadas 4.0 Internacionalinfo:eu-repo/semantics/openAccessartículoAudit feesauditor sizeauditor’s opinionaudit quality