Abstract: In response to the prominent problems of inadequate and unbalanced old-age security for the current flexible workers, there is an urgent need to accelerate the development and improvement of a multi-pillar pension system tailored to this group. Distinct from the lack of attention regarding the empirical association of public-private pension for flexible workers and the insufficient attention to the fairness of multi-pillar pension in existing research, this article examines the relationship between public and private pensions among flexible workers and its mechanism from the micro-individual level, exploring its pension fairness outcome. Using data from the 2015, 2017, and 2019 China Household Finance Surveys (CHFS), we found a complementary effect between public pension and private life insurance participation among flexible workers. Compared to the Enterprise Employees’ Basic Pension Insurance (EEBPI), the Urban and Rural Residents’ Basic Pension Insurance (URRBPI) showed a more positive correlation with flexible workers’ private life insurance participation. URRBPI preferred to boost flexible workers’ private life insurance purchase through current contributions and expected benefits, while EEBPI tended to promote it through financial literacy. Upper-middle-income URRBPI enrollers were the primary drivers of the complementary relationship. The mixed public and private pensions were not friendly to low-to-middle-income flexible employment groups, but possibly improved the expected pension for some middle-income flexible workers and narrowed the pension gap between groups covered by different public pension systems, as well as between flexible and formal workers. It is recommended that flexible workers be integrated into the "dumbbell-shaped" multi-pillar pension structure, with various measures implemented to promote fairness in the pension system.

Key words: flexible workers, public pension, private pension, multi-pillar pension system, fairness