The implementation and start-up of economic activities that generate wealth and employment in any municipality require obtaining municipal licenses and authorizations for which the drafting of a technical activity project is mandatory. All the interested parties benefit from the regulatory compliance with the urban and environmental legal requirements established by the municipalities for this type of projects. However, the numerous non-compliances detected in the "a posteriori" inspections carried out by the municipal technicians are causing that in many Spanish municipalities a high percentage of these projects are not viable and are paralyzed due to non-compliances in aspects such as accessibility for people with disabilities, incorrect location of the machines of the different facilities, smoke and gas outlets, lack of acoustic insulation, etc. The consequence of this situation is the enormous delay in the opening of the establishments, or even that some of the promoters of these projects desist from undertaking the activity. In response to this serious problem, a Knowledge-Based System (KBS) is proposed that would significantly improve the legalization system of economic activity projects processed by a responsible declaration in Spanish municipalities.