This chapter investigates the role of whistleblowing in shaping organizational perceptions of conformance, with a particular focus on the practice of fictitious invoicing. Unlike fictitious accounting—where financial data is manipulated by accountants—fictitious invoicing involves the client generating fraudulent bills to reduce tax obligations and redirect funds, often under the radar of regulatory scrutiny. The chapter uses a central case study in which the whistleblower emerged from within the offending organization, highlighting how insider knowledge can expose unethical practices. It further examines concepts such as accountants’ reporting responsibilities, crime signal detection, convenience theory, agency risk, and whistleblowing intentions, offering a multifaceted understanding of how whistleblowing operates as a mechanism for restoring or reinforcing conformance.