Art. 2 (Taxes covered) of the OECD Model Tax Convention on Income and on Capital contains a crucial requirement for the application of tax treaties. This article examines the term "tax" in Art. 2, the list of taxes in Art. 2(3), and "similar taxes" according to Art. 2(4). The article also looks at taxes on income and capital versus taxes on estates, inheritances and gifts and considers the interaction between the OECD Model Tax Convention on Income and on Capital and the OECD Model Double Taxation Convention on Estates and Inheritances and on Gifts.