The study looked at how changes in income and payroll taxes in France affected people's earnings between 2003-2006. They found that when income taxes went up, people's earnings didn't change much. But when payroll taxes increased, earnings went down. This suggests that people are more sensitive to changes in payroll taxes than income taxes. The results also show that women's decisions to work are influenced by income taxes. Overall, the findings challenge the idea that the labor market always operates perfectly and efficiently.