Objectives Epilepsy is associated with a significant burden to patients and society. We calculated the factual excess in direct and indirect costs associated with childhood- and adolescent-onset epilepsy. Methods Using records from the Danish National Patient Registry (1998–2002), we identified 3123 and 5018 patients with epilepsy aged 0–5 years and 6–20 years at the time of diagnosis, respectively. The two age groups of patients with epilepsy were matched to 6246 and 10,036 control persons without epilepsy, respectively, by gender, age, and geography. The controls were randomly chosen from the Danish Civil Registration System. Welfare costs included outpatient services, inpatient admissions, and emergency room visits based on the Danish National Patient Registry and information from the primary health-care sector based on data from the Danish Ministry of Health. This allowed the total health-care cost of epilepsy to be estimated. The use and costs of drugs were based on data from the Danish Medicines Agency. The frequencies of visits to outpatient clinics and hospitalizations and costs from primary sectors were based on data obtained from the National Patient Registry. Results Children with epilepsy had higher welfare costs than controls. The highest cost was found one year after diagnosis, with higher costs up to 10 years after diagnosis compared with controls. Children aged 0–5 years incurred greater health-care costs than those aged 6–20 years. Conclusion Epilepsy has major socioeconomic consequences for the individual person with epilepsy and for society.