The school starting age is one the factors that influence student’s educational attainment. Using a large dataset containing information of students from public schools in Portugal, it was possible to establish a positive relation between the entry age and educational outcomes, such as retentions and exam’s grades. However, deferring a child’s entry by one year does not seem to provide large benefits for students. This paper complements the analysis by understanding the main characteristics that lead to child’s deferment and reinforces the idea that educational policy is a complex issue for Governments to deal with
