Social support policy alternatives for older one-child parents in China: based on a decomposition and comparative analysis of subjective well-being

Background Older parents from China’s 150 million one-child families have experienced a decline in subjective well-being. However, the relative importance of financial and time support via family versus public channels in association with life satisfaction remains unclear, posing a challenge for policy guidance. Objectives This study aimed to evaluate and compare various social support policy alternatives for older one-child parents to identify potential measures that improve subjective well-being. Methods Data were derived from four waves of the China Longitudinal Ageing Social Survey (2014–2020), comprising 7,517 observations from 4,170 parents aged 60 and above. A random-effects generalized ordered probit (REGOP) model was employed to analyze life satisfaction, while the Shapley decomposition method quantified the relative contribution of different support factors to inequality in predicted values. Group regression models and Fisher’s tests were employed to examine heterogeneity across living arrangements and urban–rural settings. Results Family financial (β = 0.056/0.035, p < 0.01), public time (β = 0.202/0.340, p < 0.01), and family time (β = 0.038/0.034, p < 0.01) supports were significantly and positively associated with higher probabilities of being “Satisfied” and “Very satisfied,” whereas public financial support (β = 0.069, p < 0.01) was positively associated only with the “Satisfied” category. In terms of relative importance, financial support (11.94%) contributed more to subjective well-being inequality than time support (4.85%), and family support (12.01%) contributed more than public support (4.03%). Heterogeneity analyses revealed that financial and family time supports were significant and positive only in urban areas. Regarding living arrangements, the significant positive association of family time support was identified only in the solitary subgroup. Conclusion For East Asian countries like China, prioritizing financial support and strengthening family function for prevalent one-child families might be potential strategies to address dual challenges of low fertility and aging. Furthermore, support policies could also be differentiated according to urban–rural contexts and living arrangements.