Thailand is among the few developing countries that provide social pension for a significant majority of its older adults. In 2009, the government amended the Old‐Age Allowance (OAA) scheme from a means‐tested to a near‐universal social pension program. Analyzing nationally representative data from the Surveys of Older Persons in Thailand, we found significant changes over the last decade in the patterns of old‐age income sources and filial economic support for parents aged 60 and above. Results show the declining importance of children and the rising significance of OAA as the primary income source. Yet, reliance on OAA was not necessarily associated with a decline in nonmonetary intergenerational support for the parents. Findings reveal that older persons whose main income source was OAA were less likely than others to report income adequacy and positive psychological well‐being, suggesting that the scheme may have little impact in dampening inequality among older Thais.