This article assesses the impact on poverty and work incentives of a single allowance replacing some social benefits for low-income households in France. The results show that this allowance significantly reduces poverty and inequality without extra costs for public finances. The decomposition of these indicators shows, however, that some vulnerable groups of the population are disadvantaged by this kind of reform, especially single-parent families, disabled adults and impoverished elderly. Concerning work incentives, the simplification of benefits for low-income households does not make the distribution of marginal tax rates more regular nor homogeneous.