OpenFisca France

175.0.40 verified Fri May 01 auth: no python

OpenFisca Rules as Code model for France. It simulates the French tax-benefit system. Current version: 175.0.40, requires Python >=3.9. Released continuously.

pip install openfisca-france

Common errors

error ModuleNotFoundError: No module named 'openfisca_france' ↓

cause Package not installed or imported with wrong syntax.

fix

Run: pip install openfisca-france. Then import as: from openfisca_france import FranceTaxBenefitSystem

error KeyError: 'individus' ↓

cause Incorrect entity key in simulation builder.

fix

Use 'individus' (with 's') as key, and provide a list of person IDs.

error AttributeError: 'NoneType' object has no attribute 'calculate' ↓

cause Simulation object is None because builder.build_from_entities failed (e.g., missing input).

fix

Ensure all required inputs (like income, age) are set before calculating.

Warnings

breaking Version 6.0.0 introduced a major refactoring of variable names and entities. Old variable names (e.g., 'salaire_net', 'impots_directs') are deprecated or removed. ↓

fix Update variable names to current ones as per the changelog. Use `openfisca_france.variables` to list available variables.

deprecated Python 3.9 is the minimum; support for Python 3.8 was dropped in version 5.0.0. ↓

fix Upgrade Python to 3.9 or higher.

gotcha The simulation builder now requires explicit entity mapping; using `SimulationBuilder` incorrectly can lead to entity mismatches. ↓

fix Always specify entities as a dict: {'individus': [...], 'familles': [...], 'menages': [...]}. Do not rely on automatic detection.

Imports

FranceTaxBenefitSystem

wrong

from openfisca.france import FranceTaxBenefitSystem

correct

from openfisca_france import FranceTaxBenefitSystem

Use underscore, not dot

Individu

from openfisca_france.entities import Individu

Famille

from openfisca_france.entities import Famille

Menage

from openfisca_france.entities import Menage

Quickstart

Simulate the monthly disposable income of a single person earning 2000 EUR/month.

from openfisca_france import FranceTaxBenefitSystem
from openfisca_core.simulation_builder import SimulationBuilder

# Create the tax-benefit system
tbs = FranceTaxBenefitSystem()

# Create a simulation for a single person
builder = SimulationBuilder()
simulation = builder.build_from_entities(tbs, {
    'individus': ['person1'],
    'familles': ['famille1'],
    'menages': ['menage1'],
})
simulation.set_input('age', '2026-01-01', {'person1': 30})
simulation.set_input('salaire_de_base', '2026-01', {'person1': 2000})
simulation.calculate('revenu_disponible', '2026-01')