One of the issues leading to retirement income inadequacy under the defined contribution (DC) pension scheme has been attributed to funding gaps. Funding gaps under DC occur when pension contributions as well as investment returns are not regularly credited to employees’ retirement saving accounts (RSAs). In order to determine the effect of funding gaps and life expectancy on retirement income security, this study investigated how determinants of funding gaps and life expectancy affect accumulated funds. The findings showed that employer’s compliance, role of Pension Fund Administrators (PFAs), and years of remittance defaults have a positive and significant effect on funding gaps. In contrast, the role of Pension Commission (PenCom) has negative effect on funding gaps. Meanwhile, further investigation revealed that both funding gaps and life expectancy significantly accounted for 83.1% of accumulated pension funds. These findings led to the conclusion that the active roles of PenCom have assisted in recovering up to 62.5% of funding gaps back to employees’ RSAs in Federal Universities in Nigeria. Following the adverse effect of the role of PFAs on accumulated funds, the study recommends that regulatory body should carefully monitor their activities so as to ensure total compliance that will further narrow the existing finding gaps of DC. Keywords: Defined contribution, Funding gap, Retirement income adequacy, Life expectancy.