In this paper, I discuss issues on same-sex marriage and inheritance tax, mainly based on the case of Burden v United Kingdom, Windsor v. United States of America. The Civil Partnership Act 2004 granted the same rights that married couples enjoy - including that for inheritance tax - to civil partnership couples but not to family members. In Burden's case, plaintiffs asked the European Court of Human Rights for the same tax rights as married and civil partnership couples, which do not apply to cohabiting siblings. On the other hand, in the United States, DOMA had a substantive provision : Section 3 provided that for all purposes under federal law, marriage would be defined only as the union of one man and one woman. Because of this provision, for same-sex couples exemption from the federal estate tax was denied, and therefore, the plaintiff challenged DOMA as unconstitutional. Nowadays, the controversy surrounding LGBT rights has become heated, especially about same-sex marriage. It would seem that the need to discuss LGBT rights in economic terms is becoming increasingly important.