The authors consider tax treaties and Polish domestic law, analyse the significance of Art. 31 to Art. 33 of the Vienna Convention and examine the general relevance of the OECD Model and Commentary, in particular the importance of referring to domestic law in respect of treaty provisions based on Art. 3(2) of the OECD Model Convention. The relevance of tax and other treaties is then analysed. The authors conclude by examining the significance of Community law for this topic.