This letter analyzes the impact of economic integration on capital accumulation and capital flows when countries differ in their social security systems. Funding and early retirement both foster capital accumulation relative to pay-as-you-go pensions with flexible retirement. When economies integrate, both imply capital outflow possibly resulting in utility losses.
Artige, L., Dedry, A., & Pestieau, P. (2014). Social security and economic integration. Economics Letters, 123(3), 318-322. https://doi.org/10.1016/j.econlet.2014.02.027 (Original work published 2014)