Understanding the payment behavior of sociodemographic groups is important for public institutions in designing inclusive policies. Thus, public institutions regularly conduct payment surveys to monitor the payment behavior of these groups. However, such surveys are costly, conducted infrequently, and limited in the number of participants. This paper presents a methodology that enables policy-makers to monitor the payment behavior of sociodemographic groups with card data while complying with privacy rights. Specifically, it provides a correlational analysis of payment behavior across sociodemographic groups, demonstrates the potential of payment data to infer sociodemographic information and proposes a methodology for enriching card data with this information. This paper reveals that sociodemographic groups exhibit different payment behaviors, that groups can be inferred from payment data, and that anonymized card data can be enriched with sociodemographic information.