Substantial or non-substantial change? How to tell before you modify your activity

Why getting the classification right matters

A new production line, additional storage, a change of raw materials or a new emission source all modify an activity that already holds an environmental authorisation or licence. Law 20/2009 requires both substantial changes and non-substantial changes with effects on the environment to go through an administrative procedure, so that the permit always reflects what the company actually does.

If something the authorities regard as substantial is processed as non-substantial, the file is sent back and the works or the start-up are delayed. If it is simply not processed at all, the company is exposed to penalties.

The three types of change

• Substantial: for activities in Annexes I.1 and I.2, it is subject to an environmental authorisation and to a decision on whether an environmental impact assessment is required. For Annex II activities, it is subject to an environmental licence.
• Non-substantial with effects on people or the environment: the operator submits it to the environmental authority, which assesses whether or not it is substantial. If the authority considers it non-substantial, or does not say otherwise within one month, the change may be carried out.
• Non-substantial with no consequences for people or the environment: no prior procedure is required, but it must be recorded in the reports of the periodic controls. In June 2025 the Catalan Government published a specific information note on this case.

Which criteria are taken into account

Article 59.2 of Law 20/2009 sets out the aspects to be assessed, according to the greater or lesser impact of the change:

• The size of the activity or activities affected.
• Production.
• The natural resources used and, specifically, water and energy consumption.
• The volume, weight and type of waste generated.
• The quality and regenerative capacity of the natural resources in the areas affected.
• The degree of pollution produced and the risk of accidents.
• The introduction of hazardous substances or an increase in their use.
• The accumulation of non-substantial changes.

What the modification project contains

1. Description of the changes
   facilities, raw materials, water and energy consumption, waste generation and any other aspect that differs from what was authorised.
2. Substantiality assessment
   of each change, justified against the current criteria and taking into account the accumulated non-substantial changes.
3. Emissions and effects
   description and quantification of the emissions generated by the changes and of their impact on the environment.
4. Drawings and technical documentation
   for the part of the installation affected, together with the relevant application or notification forms.

Who decides and how it is submitted

It depends on the regime the activity falls under. Changes to activities holding an environmental authorisation (Annexes I.1 and I.2) are processed by the Generalitat de Catalunya (Catalan Government); changes to activities holding an environmental licence (Annex II) are processed by the municipal council where the establishment is located. The application or notification is submitted electronically.

The decision or, where applicable, the acceptance of the non-substantial change becomes part of the environmental conditions the company must comply with, and which will be reviewed in the periodic controls.

Consequences of not processing it

Law 20/2009 classes operating the activity or carrying out a substantial change without the required environmental authorisation or licence as an infringement. Depending on the annex the activity falls under and the circumstances, it may be classed as serious or very serious, with fines, closure of facilities or suspension of the authorisation. Failing to make the notifications required by the authorisation or licence is also an infringement.

These situations often come to light during the periodic control, when the inspector compares what was authorised with what is found on site. Checking the classification before carrying out the change is far simpler than regularising it afterwards.

Is the law going to change?

The Catalan Government has announced on several occasions its intention to replace Law 20/2009 with a new environmental quality law, but at the date of publication of this article Law 20/2009 remains in force, with its subsequent amendments, and is the reference for processing changes in Catalonia.