Abstract Objective: This paper investigates different methodologies for assessing a country's attractiveness in terms of Corporate Income Tax. More precisely, it aims to compare the ranking proposed by the Tax Foundation's International Tax Competitiveness Index with its own methodology. Methods: The proposed methodology assesses a country's attractiveness based on the ratio of the Effective Tax Rate (ETR) to the Statutory Tax Rate (STR) and its variance. A ratio below or close to 1 indicates an efficient, stable, and predictable tax administration system. To evaluate the impact of this ratio, firm-level data from four countries (Austria, France, Poland, and Spain) from the BACH database were analyzed over five years, from 2018 to 2022. Results: Except for France, which consistently ranks as the least attractive country, significant differences are observed between the two rankings. The resulting fiscal picture differs from that presented by the Index. Conclusions: The ratio of the ETR to the STR and its variance can be a valuable tool for assessing a fiscal system and its attractiveness. It highlights the importance of understanding the interplay between statutory and effective tax rates. Moreover, it emphasizes the need for stability and predictability in the tax treatment of investments and operations. Keywords: Corporate Income tax, effective tax rate, statutory tax rate, tax rates and rankings, average statutory corporate income tax, pre-tax profits, Corporate tax rate by country