The author examines the concept of permanent establishment (PE) under Swiss tax law from a comparative Tax Treaty perspective and finds that this concept in the Federal Direct Tax Law (FDTL) is influenced by international tax law, although differences exist. He then identifies major differences between Swiss intercantonal tax law and the FDTL, and also international tax law. He is of the opinion that the PE concept of the FDTL, which is also valid in an international context, should be adopted in a Swiss intercantonal situation. He raises the question of whether the negative list of Article 5, paragraph 4 Model Tax Convention on Income and on Capital of the Organisation for Economic Co-operation and Development (MC OECD) should also be included in the Swiss tax legislation (FDTL and Federal Tax Harmonization Law {FTHL}).