The increasing use of machines equipped with artificial intelligence has caused great concern worldwide in terms of the impact of automation on existing jobs, with some studies showing that up to half of current human workers are threatened by this process. Though the replacement of human workers by machines has been experienced in the past (e.g. in the first, second and third industrial revolutions), it is believed that this time the impacts will be more drastic because, for the first time in history, machines are capable of substituting humans not only in repetitive functions but also in cognitive tasks. In addition to mass unemployment, the replacement of human workers by robots could lead to a great loss of state revenue, as revenues from taxes on wages would be reduced. It is also believed that there will be a significant reduction in the collection of indirect taxes, due to less consumption as a result of the job losses. Conversely, public expenditures are expected to increase, especially on unemployment insurance, welfare programmes, health and education. Some proposals have been made for taxing the robots; these are presented in the current article, together with some personal contributions on the subject.