Spouse labor supply: fiscal incentive and income effect,evidence from French fully joint income tax system

The aim of the present paper is to measure the labor market participation elasticity with respect to income tax rates. A very complete data base of more than 500 000 observations a year is used. This data base is a large sample of the French income tax returns. The case of spouses is studied by comparing - for very similar couples - the probability of the secondary earner to participate in the labor market depending on the other foyer incomes on the one hand and depending on the tax rate which would apply on the income of this potential work on the other hand. Results find labor market participation elasticity with respect to income tax rate equal to -0.04 and with respect to income equal to -0.30. That for, it is outlined that joint income tax schedules have a negative impact on the secondary earners participation to labor market. As secondary earners are mainly women in France, joint income tax schedules have a negative impact on women participation to the labor market. Furthermore, different elasticities are measured for different population categories. Two phenomenons appear, they confirm each other partially. On the one hand, there is a difference between secondary earners more or less constrained to participate in the labor market. The more constrained ones have weaker elasticities than the less constrained ones. On the other hand, there is a major difference between the capital holders and the others. The capital holders’ elasticity with respect to income tax rate is higher than their elasticity with respect to income. The opposite occurred for the other households.