Questão jurídica principal
Whether the consultant breached the mandate by failing to file tax returns in time and protect the client's fiscal interests.
Decisão extraída
Yes. A tax consultant must act diligently, insist on timely documents, warn of delay risks, and the consultant remained passive.
Fundamentação extraída
Under Art. 398 CO, read with Art. 321a and Art. 97 CO, the professional standard required active management of filing deadlines and necessary documents; the canton court's findings showed no timely action and no contributory fault by the client.