Input tax deduction is one of the cornerstones of the VAT system. Generally, it is invoice based. In this respect, the Turkish VAT system is no exception. In this article, the author describes the legal context and the nature of the formal prerequisites for exercising the right to deduct input tax laid down in the Turkish VAT Act in relation to the jurisprudence of the Turkish Supreme Administrative Court. The author also analyses the EU aspects of input tax deduction on the basis of the Sixth Directive provisions and the case law of the European Court of Justice.