This study investigates how prior experiences of receiving aid during disasters influence subsequent support behaviors, highlighting the concept of paying it forward in the context of large-scale disasters in Japan. Drawing on two nationwide surveys conducted after the 2011 Tohoku Earthquake (N = 1,679) and the 2024 Noto Peninsula Earthquake (N = 400), we examine how personal aid experiences shape later altruistic actions. While overall support behaviors—such as donations, sending supplies, purchasing support goods, visiting affected areas, or volunteer activities—declined in 2024 compared to 2011, individuals with prior experiences of being helped had significantly higher odds of engaging in such actions, with odds ratios ranging from 2.3 to 2.4. Logistic regression analyses revealed that this effect was especially strong among those with less than a college degree, suggesting that the experience of being helped can substitute for limited educational resources in motivating support. The findings also show that the influence of prior aid experiences has grown over the past decade, reinforcing the expansion of pay-it-forward networks where past recipients become future supporters. By incorporating the concept of paying it forward, this study challenges traditional resource-based models of altruism and emphasizes the agency of survivors in building social support systems. These findings underscore the importance of fostering grassroots support networks that empower survivors as future contributors—especially in societies increasingly exposed to large-scale hazards.