Penalty proportionality: minor, easily rectifiable tax documentation errors should attract warning-level sanctions and procedural safeguards. General disciplinary principles require that penalties for minor or easily rectifiable documentation errors made without fraud or gross negligence be proportionate and limited, while fixed-sum or fixed-percentage penalties remain exempt from these safeguards. Procedural protections mandate notice to show cause, a reasonable opportunity to be heard, and an explanation in penalty orders specifying the breach and legal basis; voluntary pre-discovery disclosure is a potential mitigating factor.