Depression affects everyday decision-making, yet it remains unclear if such effects depend on the decision context or fluctuate over time. In this repeated-measures study, online participants completed a social exchange task (ultimatum game) and a non-social reversal learning task at baseline (n=236) and 1-month later (n=131). Mood symptoms were assessed using the Beck Depression Inventory and the Positive Valence System Scale. Psychiatric symptoms were stable over time, and dropout was unrelated to symptom severity. Mixed-effects regression revealed consistent behavioral effects of depressive symptoms—while controlling for anhedonia—across time points. Specifically, greater depressive severity predicted slower reaction times and reduced acceptance of unfair offers in the ultimatum game. An interaction between depressive and anhedonic symptoms on mood ratings emerged at baseline but did not replicate at follow-up. There were no consistent significant effects of depression on the non-social reversal learning task across time points. These findings highlight the longitudinal stability of depressive symptoms on social decision-making.