In this article, we present the wald tc command, which computes the maximum regret (MR) of a user-specified statistical treatment rule that uses sample data on realized treatment response (and optionally an instrumental variable) to determine a treatment choice for a population. Because the outcomes of counterfactual treatments are not observed and treatment selection in the study population may not be random, decision makers may be able only to partially identify average treatment effects. wald tc allows users to compute the MR of a proposed statistical treatment rule under a flexible specification of the datagenerating process and determines the state that generates MR.