The corporate pension system had established by reforming the Labor Standard Act of 1987, and insurance companies started to sell the pension contracts on April 1, 1999 in Korea. Later, other financial institutes including banks and fund trust companies, etc. followed on April 24, 2000. In order to provide the underlying sources for amending the current corporate pension accounting standards and related tax raws, this paper examined empirically characteristics of firms electing early adoption of the newly established corporate pension system in Korea and discussed the implications why some firms may elect the system. In manufacturing industry, 125 firms among 398 firms from 1994-1999 data were set as "early adaption" and the others were set "delayed adaption". Univariate tests and multivariate logistic regressions were run. As the result, cash flow, reserved-out of retirement benefit allowance ratio, firm size, and wage level were found to be significant factors to early adaption.This result implies that: First, it is necessary to rule expected overfunding in both accounting standards and taxation because firms have the motives to use pension system as financial slack by business tax benefit. Second, accounting standard interpretation No.13-27 seems to be relevant to rule the case in which firms would transfer the collective retirement insurance to corporate pension. Third, differential reporting standards according to firm size can be recommended. Forth, tax rate may be a significant factor * Professor, School of Business, Chung-Ang University.