The book analyzes the problems in the application of the Foreign Controlled Entities Regime (ECE Regime) in Colombia, established by Law 1819 of 2016. Inspired by the OECD and its BEPS action, this regime seeks to control passive income generated by companies abroad that are controlled by Colombian residents. However, the regulation is complex and presents ambiguities in the definition of key concepts such as passive income and control, which may lead to diverse interpretations. The lack of a specific regulatory decree aggravates the situation, leaving many concerns unresolved and generating confusion among taxpayers and tax authorities. The paper is based on a qualitative approach, analyzing legislation and DIAN pronouncements, and aims to identify the problems in the application of the regime for legal entities in Colombia. It is expected that this analysis will contribute to a better understanding and implementation of the ECE Regime in the Colombian tax context.