No major deal by transnational corporations (TNCs) takes place without consideration of the tax implications and optimal tax arrangements. Indeed, a great many investments and transactions are formulated on the basis of analysis of tax advantages, very often due to anomalies in the interaction of different tax systems, and lawyers play a key part in devising such transactions and financings. The basic patterns and strategies for minimiz­ ing tax liability of international investments were developed by the large TNCs themselves, and in-house specialists still play a major strategic role in tax planning for such large corporations, using local firms of accountants or lawyers where necessary for tax compliance procedures. However, com­ petitive pressures caused the increasingly widespread use and availability of facilities for international tax avoidance.