24 February 2011 Internal T.I. 2010-0387901I7 - Permanent Establishment -- summary under Article 5

Paragraph 3 of the OECD Model Convention (providing that "a building site or construction or installation project constitutes a permanent establishment only if it lasts more than twelve months") represents a stand alone test for determining whether a site or project qualifies as a permanent establishment, so that once the requirements of that paragraph have been satisfied, a permanent establishment will be found to exist and it is not necessary to consider whether the "basic rule" in paragraph 1 has been satisfied.