In its first court case against the EU, which sees Brussels attempting to extract millions of pounds from the UK, Britain has prevailed.
The bloc claims that the UK tax system permits unlawful exclusions, thus it is attempting to recoup the funds from the London Stock Exchange.
The EU competition enforcer said the UK's Controlled Foreign Company (CFC) rules set up to try and encourage foreign companies to invest in Britain gave some companies an illegal advantage.
But the Court of Justice of the European Union (CJEU) has fallen on Britain's side in the dispute.
The court said: "The Commission and the General Court erred in law in finding that the rules applicable to CFCs constituted the appropriate reference framework for examining whether a selected advantage had been conferred.
The Court recalls that the Commission ... is in principle required to accept the Member State’s interpretation of the relevant provisions of its national law, unless it is able to establish that another interpretation prevails in the case-law or the administrative practice of that Member State."
The EU did not name any of the companies they deemed to have gained an illegal advantage from the tax scheme.
BBA Aviation, Chemring, Daily Mail & General, Diageo, Euromoney, Inchcape, Meggitt, Smith & Nephew and WPP have mentioned the EU investigation in their accounts.