This article focuses on determining when software payments are deemed to be royalties in tax treaties pursuant to the Commentary on Art. 12 (Royalties) of the OECD Model. The article first discusses the importance of classifying software payments as royalties and sets out the main studies and reports on this topic. The article also examines the question whether software payments may be included in the wording of the royalty concept which refers to "the use of, or the right to use, any copyright of literary, artistic or scientific work". Finally, the article looks at the aspects which should be taken into account or disregarded in classifying software payments as royalties.