Despite several modifications and the wide use of the monetary incentive delay paradigm (MID; Knutson et al. in J Neurosci 21(16):RC159, 2001a) for assessing reward processing, evidence concerning its application in children is scarce. A first child-friendly MID modification has been introduced by Gotlib et al. (Arch Gen Psychiatry 67(4): 380-387, 2010); however, comparability in the results of different tasks and validity across different age groups remains unclear. We investigated the validity of a newly modified MID task for children (CID) using functional magnetic resonance imaging. The CID comprises the integration of a more age appropriate feedback phase. We focused on reward anticipation and their neural correlates. Twenty healthy young adults completed the MID and the CID. Additionally, 10 healthy children completed the CID. As expected, both paradigms elicited significant ventral and dorsal striatal activity in young adults during reward anticipation. No differential effects of the tasks on reaction times, accuracy rates or on the total amount of gain were observed. Furthermore, the CID elicited significant ventral striatal activity in healthy children. In conclusion, these findings demonstrate evidence for the validity of the CID paradigm. The CID can be recommended for the application in future studies on reward processing in children, adolescents, and in adults.