Article 1201 of the French Civil Code

When the parties have entered into an apparent contract that conceals a hidden contract, the latter, also known as a counter-letter, is effective between the parties. It is not enforceable against third parties, who may nevertheless rely on it.

Original in French 🇫🇷

Article 1201

Lorsque les parties ont conclu un contrat apparent qui dissimule un contrat occulte, ce dernier, appelé aussi contre-lettre, produit effet entre les parties. Il n’est pas opposable aux tiers, qui peuvent néanmoins s’en prévaloir.