The notion of what constitutes fairness has been assumed to change during childhood, in line with a marked shift from outcome-based to intention-based moral reasoning. However, the precise developmental profile of such a shift is still subject to debate. This study sought to determine the age at which the perceived intentions of others begin to influence fairness-related decision making in children (aged 6-8 and 9-11 years) and adolescents (aged 14 and 15 years) in the context of the mini-ultimatum game. The mini-ultimatum game has a forced-choice design, whereby a proposer needs to select one of two predetermined offers that a responder can either accept or reject. Due to these constraints, the procedure measures sensitivity to unfair intentions in addition to unfair outcomes. Participants needed to make judgments about how likely they would be to reject various offers, how fair they judged these offers to be, and the emotion they experienced when thinking about the offers. Contrary to previous published reports, we found that even 6- to 8-year-olds employed a sophisticated notion of fairness that took into account the alternatives the proposer had available. Crucially, decision making did not differ as a function of age. A further, and novel, aim was to trace the developmental origins of temporal asymmetries in judgments ab out fairness by testing the implications of adopting a past or future temporal perspective. Across all ages, we found no evidence that fairness-based decision making varies as a function of temporal location.