Rules, Computation and Politics: Scrutinizing Unnoticed Programming Choices in French Housing Benefits

Social benefits and taxes are computed by machines in almost all developed countries. The size and complexity of the programs implementing these computations is big enough that serious questions can be raised about their safety, correctness and faithfulness to the law. In this presentation, we will share our experience translating the rules for the French housing benefits computation into executable code with the Catala domain-specific language. This formalization effort cast light on several ambiguities and non-neutral choices that had to be made in order to produce the code. Overall, we call for more transparency and accountability of the administration regarding the software they operate whose task is to massively apply the law.