A Financial Assessment and Development of Estimation Model for the Basic Livelihood Security System This study reviewed financial assessment methods, financial estimation models, and considerations to make in introducing a financial estimation model, for the Basic Livelihood Security System(BLSS). In the long term, this study is aimed at establishing a financial estimation model for the social security system. The financial assessment frame was analyzed in three aspects, including efficiency, effectiveness and equity, following a proposal made by international organizations such as the OECD and the World Bank and preceding studies. The BLSS has reduced the poverty rate for all households in Korea by 8% point on average for three years covered by the study. The poverty rate for households with single parents or members with disabilities has dropped by minimum 13% and maximum 20% after the introduction of the BLSS. The efficiency of poverty reduction was measured to be 78% on average for three years covered by the study. This means that 78% of the total BLSS benefits - exceptmedicaid - was paid out for the purpose of reducing poverty gap. However, there still remains households left out of the BLSS, with one or two-person households turning out to be the biggest such group. The basic financial estimation model for the BLSS needs estimations about beneficiary households, recognized income, and the minimum cost of living, and, in estimations, should take into account internal changes made to the BLSS such as changes in the eligibility criteria as well as external changes such as inflation, the unemployment rate and the demographic structure.