Autism spectrum disorder (ASD) is characterized by a core deficit in theory-of-mind (ToM) ability, which extends to perturbations in moral judgment and decision-making. Although the function of the right temporoparietal junction (rTPJ), a key neural marker of ToM and morality, is known to be altered in autistic individuals, the neurocomputational mechanisms underlying its specific impairment in moral decision-making remain unclear. Here, we addressed this question by employing a novel fMRI task together with computational modeling and representational similarity analysis (RSA). ASD patients and healthy controls (HC) decided in public or private whether to incur a personal cost for funding a morally-good cause (Good Context) or receive a personal gain for benefiting a morally-bad cause (Bad Context). Compared with HC, individuals with ASD were much more likely to reject the opportunity to earn ill-gotten money by supporting a bad cause than HC. Computational modeling revealed that this resulted from unduly ...