The basic structure of the assessment of property under the current inheritance and gift tax law is a simple one in which it is based on the market price, but in cases where it is impracticable to calculate the current market price, complementary valuation methods are used as an exception. However, the abstractness of the concept of the market price and what specific extent to which it should be recognized as the market price are complex and difficult issues. Because of this, many controversies arise between taxpayers and tax authorities.
 With the purpose of the improvement of fair taxation, Korea's inheritance and gift tax law has continuously expanded the scope of what can be recognized as the market price based on the principle of the market price. This reflects the reality that there is an inevitable conflict of interest between taxpayers who prefer complementary valuation methods due to the property valuation method of the inheritance and gift law, which allows complementary valuation methods to be exceptionally applied only in cases where it is impracticable to calculate the current market price and the realistic price rate of the officially assessed real estate price that is far below the market price, and tax authorities.
 The value recognized as the market price under the current inheritance and gift tax law can be divided into four categories, which are the relevant property and the case value for similar property within the principle of assessment period, and the relevant property and the case value for similar property within the extended evaluation period.
 This study deals with ‘the application of similar case values to apartments, etc.’ which is controversial regarding the scope of market recognition and ‘whether the appraised value requested by the tax office after the reporting date for non-residential real estate, etc. is recognized as market price or not’ targeting real estate, which accounts for a high proportion of inherited and gifted properties. In relation to this, there are many criticisms that it is not only against the principle of fair taxation, but it can also infringe on the taxpayer's predictability in terms of that excessive taxation is imposed on some taxpayers for properties with the same burden due to the existence of a sale price of similar property traded by another person by chance or an appraisal request based on the arbitrary judgment of the tax authorities, etc.
 It is not easy in reality to establish clear and consistent standards that all taxpayers can agree on when calculating the market price of inherited or gifted property whose ownership is transferred gratuitously. However, it is essential that the tax authorities continue to make efforts to accept criticism of existing taxation practices as article 15 of the enforcement rules of the inheritance and gift tax law legislate the scope of similar property in apartments in detail.
 This study analyzed major issues in taxation practice by analyzing the provisions of the inheritance and gift tax law and recent precedents regarding the scope of provisional recognition of the market price and sought ways to improve them. The main tax issues in applying the case value for similar property to apartments, etc. are; first, exclusion of application of the case value for similar property if there is a case value for the relevant property, second, the period of market recognition for the case value for similar property, third, criteria for judging similarity, and fourth, whether there are special circumstances for price fluctuations.