modify_social_security_taxation.py

# -*- coding: utf-8 -*-

# This file defines a reform.
# A reform is a set of modifications to be applied to a reference tax and benefit system to carry out experiments.
# See https://openfisca.org/doc/key-concepts/reforms.html


# Import from openfisca-core the common Python objects used to code the legislation in OpenFisca
from openfisca_core.model_api import *


class modify_social_security_taxation(Reform):
    # A reform always defines an `apply` method that builds the reformed tax and benefit system from the reference one.
    # See https://openfisca.org/doc/coding-the-legislation/reforms.html#writing-a-reform
    def apply(self):
        # Our reform modifies the `social_security_contribution` parameter, which is a scale.
        # This parameter is declared in `parameters/taxes/social_security_contribution.yaml`.
        #
        # See https://openfisca.org/doc/coding-the-legislation/legislation_parameters.html
        self.modify_parameters(modifier_function=self.modify_brackets)

    def modify_brackets(self, parameters):
        # This function takes an argument `parameters` which is a in-memory representation
        # of the YAML parameters. It can be modified and must be returned.

        # Access the right parameter node:
        brackets = parameters.taxes.social_security_contribution.brackets

        # Add 0.1 to the rates of the second bracket, keeping the same thresholds:
        for rate in brackets[1].rate.values_list:
            rate.value += 0.1

        # Remove the first bracket:
        del brackets[0]

        # Add a new bracket with a higher tax rate for rich people:
        new_bracket = Bracket(
            'new_bracket',
            data = {
                'rate': {'2017-01-01': {'value': 0.4}},
                'threshold': {'2017-01-01': {'value': 40000}},
                },
            )
        brackets.append(new_bracket)

        return parameters