Semantic versionning guidelines

Before merging your contribution to an openfisca package, you are required to increment the version of this package.

The semantic versionning convention, applied here, requires you to:

Given a version number MAJOR.MINOR.PATCH, increment the:

MAJOR version when you make incompatible API changes,

MINOR version when you add functionality in a backwards-compatible manner, and

PATCH version when you make backwards-compatible bug fixes.

It is thus crucial to determine whether your changes are backwards-compatible. If, during a hackathon, a contributor has written a reform to Openfisca, would this reform still work after adding your changes ?

Examples in Openfisca context

Country package (e.g. openfisca-france)


  • Correcting an error in a formula.
  • Correcting the value of a parameter.


  • Introducing a new formula.
  • Introducing a parameter.


  • Renaming or deprecating a variable.
  • Changing the default value of a variable.
  • Deprecating a parameter.
  • Changing the sctructure of the parameter tree.