Audit partner tenure, audit firm tenure, and discretionary accruals: Does long auditor tenure impair earnings quality?

Mandatory audit partner rotation has been adopted in some countries while audit firm rotation is still being debated in many places. Most of the extant research on the relation between auditor tenure and earnings quality provides evidence at the audit firm level. However, since audit firm tenure is correlated with partner tenure and audit firm rotation is more costly than partner rotation, it is important to know whether earnings quality is related to audit firm tenure, partner tenure, or both. We investigate this issue using a sample of Taiwanese companies for which the audit report must be signed by two partners with their names disclosed in the report. Using performance-adjusted discretionary accruals as a proxy for earnings quality, we find that the absolute and positive values of discretionary accruals decrease significantly with partner tenure. After controlling for partner tenure, we find that absolute discretionary accruals decrease significantly with audit firm tenure. Our findings are not consistent with the arguments that earnings quality decreases with extended audit partner tenure and that audit firm rotation in addition to partner rotation would improve earnings quality. Our results are robust to alternative Ways-of measuring partner tenure under the dual signature system. However, since the audit reports do not disclose which partner is responsible for maintaining the auditor - client relationship, measurement errors in partner tenure remain an issue that cannot be fully addressed in the context of our study.