France opens source code of t…

France opens source code of three new simulators


France is continuing to improve its fiscal transparency by opening the source code of three new algorithms, and has promoted use of this code through a hackaton called #CodeGouv.

The three algorithms are used by the French administration to calculate:

  • The cost of a car registration document which can change according to the geographical location or the type of vehicle;
  • The legal bonus of an apprentice, which can vary according to the number of working hours;
  • The penalty rate. The simulator assesses the interest the French administration should pay if payments are delayed.

This source code was opened by DILA (Direction de l’Information Légale et Administrative – Directorate of legal and administrative information), in collaboration with Etalab, the French open data agency.


This hackathon followed the CodeImpot event, organised last April in Paris. This hackathon aimed at re-using and improving the newly-opened source code of a tax calculator. It was the first time France opened one of the 54 simulators listed on, the website dedicated to French administration. Etalab said that administrations that have developed simulators are invited to open their own algorithms.

During the CodeGouv Hackaton, which took place on October 13, public agents, start-ups and associations worked on projects to “help improve the state’s simulators and create new prototypes”, Etalab said on its blog. For example, the creation of a new simulator to anticipate the needs of administrations that want to open their own simulators was among the projects. Among others, we find the development of a simulator to assess hiring costs in France, based on; and the improvement of the fiscal micro-simulator OpenFisca to include the algorithm to calculate the legal bonuses of apprentices. Creating a new interface for, a consultation platform, was also on the agenda, Etalab writes.

Other tools were also provided for the hackathon: the source code of DILA’s simulator generator (called G6K) and of the platform.

The opening of administrations’ source codes is part of the new Law for a Digital Republic (Loi pour une République Numérique).

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