This paper analyzes the costs associated with institutional harmonization in Eastern Neighborhood Policy (ENP) countries transitioning toward EU norms, highlighting that the public sector will face costs in adapting regulations while the bulk of the financial impact will fall on private enterprises. Using comparative analysis from Central and Eastern European (CEE) countries, the study estimates the potential costs for ENP nations through extrapolation of data related to pre-accession financial support and private compliance. The findings underscore that while initial compliance may incur substantial expenses, the long-term economic benefits of harmonization are typically significant.