가족합산과세제도의 합헌성 ― 종부세 사건에 대한 헌재판결의 타당성검토를 중심으로 ―

In many countries, married taxpayers can choose between filing a joint tax return or a separate tax return. The couples have to deicide how to report their income. By filing a joint return, the couples calculate their income together and report it on a sheet to tax office. The Married Filing Separately reports their income separately like unmarried. Usually, the joint return provides more tax benefits than filing separate returns. But exceptionally, it could worse than single return. In that case, the couple choose filing separately. It is the right of taxpayers to choose joint return or single return. So far, the Korean Income Tax Law does not allow married taxpayers to file their income tax jointly. Even the Korean Constitutional Court decided that joint return in Comprehensive Real Estate Tax(CRET) was unconstitutional. After the decision of the Constitutional Court, the congress changed the statute. Now, only single return is acceptable. This research is focused on why the Korean Constitutional Court declared the jonit retun in CRET as unconstitutional, whether the decision of the Korean Constitutional Court on CRET is correct. The Constitutional Court did not recognize that the calculation of the tax objects jointly and the higher tax burden caused by joint return are two different things. The calculation of the tax objects jointly is constitutionally allowed. The main problem of joint return in CRET is the higher burden caused by joint return. U.S., Germany and France allow married taxpayers to file jointly, but joint return in that countries does not cause the higher tax burden in normal cases. If we introduce that kind of joint return, it is undoubtedly constitutional.