What are the contractual terms called that exist but are not formally written down?

The correct term for contractual terms that exist but are not formally written down is "implied terms." Implied terms are those provisions that are understood to be part of a contract even if they are not explicitly stated. These terms are often based on the nature of the agreement, the intentions of the parties involved, or legal principles and statutes that govern the agreement.

For example, in many jurisdictions, there may be implied terms concerning the quality of goods or services provided in a contract for sale or service, ensuring that they meet certain expected standards, even if those specifics are not documented in the contract itself.

This concept is crucial in legal contexts, as it helps protect parties in agreements by providing a standard framework that parties can rely on, even when not all terms are laid out in writing. Understanding implied terms is essential for effective contract management and ethical procurement practices, as they contribute to fair dealings and ensure that the expectations of all parties are met, fostering trust and cooperation in business relationships.