The authors examine the consequences of non-performance in smart contracts, analysing possible costs and their impacts on the rational choice of the parties under Law and Economics’ theory. Exploring the possibilities of non-performance in contractual and obligational theory, this chapter analyses the possible outcomes, advantages and disadvantages of using smart contracts, especially in case of deferred performance, concluding that in certain situations, the use of smart contracts might be costlier than traditional language written documents, and therefore, should be avoided.