The Tax on Constructions, Installations and Works is a local tax that, together with the Tax on the Value of Urban Land, forms the group of optional taxes provided for by the Local Treasury Law. This optional nature in terms of its establishment means that municipal entities must regulate, through Fiscal Ordinance, the different aspects of the tax to consider it established and enforceable.

It is a tax of an indirect nature (mention that this legal definition that appears in the Law, could be considered incorrect, since it can only be direct or indirect a "tax", since the heading "Taxes" includes other public law income such as Fees or Special Contributions), whose object of taxation is the manifestation of wealth that is evident when any construction, installation or work that requires the appropriate municipal license is carried out. Thus, not all construction, installation or work is subject, but only those that require obtaining a license, whether for construction or urban planning.

The taxable event requires the cumulative concurrence of the following requirements:

The carrying out of any construction, installation or work owned by the State, the autonomous communities or local entities, which are intended directly for roads, railways, ports, airports, hydraulic works, sanitation of towns and their wastewater, is considered exempt, whether it is new investment or conservation works.

Taxpayers of this tax, as taxpayers, are natural or legal persons and entities without legal personality (civil companies, existing estates, communities of property and other entities that constitute an economic unit or separate assets susceptible to taxation), who are owners of the construction, installation or work, whether or not they are owners of the property on which these are carried out.

The people who finance the construction, installation or work will have the status of owners of the works.

The substitute is an independent and distinct figure from the taxpayer. In the event that the construction, installation or work is not carried out by the taxpayer, the taxpayer will be considered a substitute taxpayer: