A recent U.K. Supreme Court ruling has thrown into question the treatment of Delaware limited liability companies (LLCs) for U.K. tax purposes.  The unanimous final judgment in the case reversed the previous decisions of the Upper Tribunal and the Court of Appeal and upheld the original ruling of the First-tier Tribunal.  The decision addressed the question of whether a member of a Delaware LLC was entitled to double taxation relief on his share of the LLC’s profits, which had been taxed in the U.S. and remitted to the U.K.  This article provides relevant background information; summarizes the Supreme Court’s decision and reasoning; and considers the implications of the judgment for hedge funds organized as Delaware LLCs and investors in such funds.  For more on U.K. taxation, see “U.K. Disguised Fee Rules May Result in Increased U.K. Taxation of Investment Fees to Individuals Affiliated with Hedge Fund Managers (Part Two of Two),” Hedge Fund Law Report, Vol. 8, No. 16 (Apr. 23, 2015); and “Potential Impact on US Hedge Fund Managers of the Reform of the UK Tax Regime Relating to Partnerships and Limited Liability Partnerships,” Hedge Fund Law Report, Vol. 7, No. 10 (Mar. 13, 2014).