The inclusion of shipping in the European Union Emissions Trading System (EU ETS) introduces significant operational and financial challenges, as ship operators face direct costs linked to carbon emissions. This study establishes a comprehensive methodology for assessing the EU ETS impact at the ship level, focusing on vessel-specific data collection and validation, operational parameter analysis, emissions quantification, and calculation of EU allowance requirements. Using real data from ship operation, covering a period from 2021 to mid-2024, the research ensures the credibility and accuracy necessary for informed decision-making. The findings emphasize that ship operators must adopt robust systems to continuously monitor and verify their EU ETS exposure, enabling compliance and cost-effective operational adjustments. By bridging regulatory requirements and practical implementation, this study provides a valuable framework for navigating the complexities of maritime decarbonization under the EU ETS framework.