In a model in which agents differ in wages and preferences over labor time-consumption bundles, we study labor income tax schemes that alleviate poverty. To avoid conflict with individual well-being, we require redistribution to take place between agents on both sides of the poverty line provided they have the same labor time. This requirement is combined with efficiency and robustness properties. Maximizing the resulting social preferences under incentive compatibility constraints yields the following evaluation criterion: tax schemes should minimize the labor time required to reach the poverty line. We apply this criterion to European countries and the US.