On June 5, 2012, the Fifth Circuit Court of Appeals created a circuit split with the Third Circuit by holding in Entergy that the UK Windfall Tax is a creditable foreign income tax under section 901. The Third Circuit recently had held in PPL that the UK Windfall Tax was not creditable on the same issue. This decisionhas ramifications for the creditability of foreign taxes because of its emphasis on a substance-based application of the test under Treas. Reg. § 1.901-2. Taxpayers should consider how both cases could impact their ability to claim foreign tax credits.