Contributed to the govpf/openfisca-pf repository by implementing a property tax penalty system, enabling accurate calculation of fixed penalties and late payment interest based on declaration dates and prior tax amounts. The work involved backend development using Python and YAML, introducing new parameters and variables to the policy engine and expanding test coverage to validate the new mechanism. Additionally, maintained repository hygiene by updating the .gitignore file to exclude IDE-specific configuration files, ensuring a cleaner codebase and smoother onboarding for collaborators. The contributions focused on both enhancing tax calculation logic and improving the maintainability of the project’s development environment.