Of non-legal obligations, collateral assurance is a bond made over and beyond the deed itself, for the performance of an agreement, or covenant, made between two individuals; so called, for being external, and without the nature and essence of a covenant. A collateral assurance is separate but subservient to the principal contract.
In the context of agreements between individuals, a collateral guarantee serves as extra insurance for the fulfillment of promises or commitments. This type of arrangement exists outside of the main contract and provides added security.