This paper examines the determinants of variability in effective corporate tax rates before and during the public finance crisis in Tunisia, a country that was and remains on the agenda of international financial institutions.Analyzing firm-level data for the period 2005-2018, we find with a significant level of significance that specific firm characteristics, including firm size, leverage, capital intensity, and inventories, affect the level of corporate effective tax rates.Our results also indicate that as corporate effective tax rates increased in the period following the onset of the financial crisis, their association with certain firm-specific characteristics was also affected.