This thesis investigates the judicial cases in which the beneficiaries who were levied estate tax after receiving the death benefit of life insurance based on the Substance over Form Principle. The investigation starts from the basic description including the meaning and function of insurance, insurance law and insurance contract, to illustrate insurance types, terms and definitions, product structures, and the legal taxation regarding insurance related persons. Then, the thesis summarizes seven research conclusions and proposes four suggestions according to our analysis of the Judgment No.227 of the Supreme Administrative Court in 2013, in which the tax and judicial agencies maintain death coverage of the life insurance as savings insurance product, and levy the estate tax on add-on additional benefits.