Do automated or artificial intelligence systems follow the law? What design choices can the law make to encourage legal compliance by robots? Tax law has some experience with these questions.Algorithmic tax compliance robots, such as TurboTax or H&R Block Online, appear to break taxpayer data law, and they do not systematically encourage taxpayer honesty. On the other hand, they appear to interpret substantive tax law conservatively, in a way that minimizes audit risk. Market incentives produce these results, since tax compliance robots generally have not been charged with direct liability for legal violations. Legal design responses require nuance and variation in order to fit the diversity of outcomes produced by such robots’ operation in their markets.