The Emergence and Consolidation of Microsimulation Methods in France[L’émergence et la consolidation des méthodes de microsimulation en France]

The purpose of this paper is to trace the gradual emergence of microsimulation models dedicated to the analysis of tax and social security policies in France since the mid- 1960s, as well as their subsequent consolidation since the mid-2000s. A brief outline of these models is given using the static/dynamic distinction. A connection is made between the construc- tion of the Mir model (standing for Modèle de l'impôt sur le revenu, an income tax model) and the development of the survey Revenus fiscaux. Then we distinguish two periods: An initial period that saw a proliferation of such models and a second period, of standardisation, during which the Ines model has acquired a central position. Besides ongoing evaluations (of minimum income and pension schemes, insurance for long-term care), the most recent expectations in this area relate to the ex ante evaluation of measures designed to accelerate the ecological transition and of universal income-type schemes. Finally, we underline that the recent replacement of all the periodic declarations made by employers to various administrations by a unique declaration (the Déclaration sociale nominative, or DSN) significantly renews the range of administrative sources capable of feeding into these models.