Treballs Finals del Doble Grau d'Administració i Direcció d'Empreses i de Dret, Facultat d'Economia i Empresa i Facultat de Dret, Universitat de Barcelona, Curs: 2016-2017 , Tutor: Javier Vázquez Grenno(spa) El Impuesto municipal sobre el Incremento de Valor de los Terrenos de Naturaleza Urbana ha sido recientemente cuestionado a raíz de la Sentencia del Tribunal Constitucional núm. 27/2017 de 16 de febrero de 2017. Sobre esta base, se realiza un análisis jurídico de los principios básicos del sistema tributario español en general y se estudia la estructura y configuración del citado impuesto en particular. Asimismo, se examina el primer fallo del Tribunal Constitucional en relación al citado impuesto, que es confirmado al poco tiempo por otras dos decisiones. Por otro lado, se realiza un análisis económico del comportamiento de la recaudación del impuesto durante el periodo 2005-2015 en el conjunto del territorio español y en la ciudad de Barcelona.(eng) The municipal tax related to the increase of value of urban land has recently been questioned due to a ruling of the Constitutional Court on February 16th, 2017. It is a tax on the profit a person makes when transferring an urban land or rights in rem. However, even though Local Councils should only raise the tax in situations of gains, people that incur losses have to pay it anyway. For this reason, the Constitutional Court, for the first time regarding this municipal tax, has declared some articles of the Provincial Law 16/1989 to be unconstitutional. A few weeks after this first ruling on February 16th, the Constitutional Court declared unconstitutional the same articles of the Provincial Law 46/1989 and the Royal Legislative Decree 2/2004. In this paper I analyse, from a legal point of view, the Spanish tax system. I focus on its regulation, its principles and which are the types of income for local authorities. I study how the tax on the increase of value of urban land is structured in the Spanish legal system. To finish with the legal perspective, I analyse the first ruling of the Constitutional Court regarding the tax, which will change its future. In a more economic point of view I examine the behaviour of the tax income during the period 2005-2015, differentiating Spain as a whole from a large city such as Barcelona. This analysis reveals the incoherencies of the tax on the increase of value of urban land where revenues of Local Councils in Spain have increased even though some people have transferred urban land incurring in losses. In other words, although it is a tax on an increase, in the end, all transmissions end up being charged. To conclude, I show some alternative solutions to the way the tax on the increase of value of urban land is configured.