A summary in English of the book Los principios y normas de armonización fiscal del Concierto Económico (The Principles and Rules of Fiscal Harmonization of the Economic Agreement) (Fundación BBV, page 179). It constitutes an in-depth and detailed study of the law regulating the financial and tax relations between the autonomous region and central government, particularly in the area of fiscal harmonization, and was requested by the BBV Foundation from the European Institute for Administration.