According to the regulations, when the Public Administration (PA) responsible for a specific procedure has expressly established specific forms for submitting applications or procedures, interested parties are obliged to use them.
Well, the entities that process through EACAT may be considered interested parties in the administrative procedure and, therefore, the previous provisions may also apply to them (it depends on the criteria of the PA responsible for the service).
In this sense, the user entities of EACAT can define specific services to facilitate electronic inter-administrative processing that include the forms for the different procedures that make up the service, which are incorporated into the EACAT Procedures Catalog.
However, when there is no specific procedure in the Catalogue, the entities using EACAT have the generic submission at their disposal, to send the documentation/information that they want to send to the destination entity.
For this reason, it is recommended that before sending the generic submission, you make sure that no specific procedure or specific form with mandatory use has been enabled.
For more information, see the following entries in the EACAT Support Portal:
Law 39/2015: art. 16 and 66