Preliminary protection is carried out in the field, in registry offices, where the archives are created, through supervision and professional assistance with filing and maintenance, selection and registering of the whole documentation of an entity.

The territorial competence of the Archives comprises the area of the Assembly of the City of Belgrade, that is, the ten urban and seven outlying municipalities. The real competence covers the documentation of all legal entities operating on the territory of the City of Belgrade which are not of republican or federal importance. All in all, 2,454 registry offices have been identified which are continuously supervised (or had been supervised) by the Archives in connection with the filing of the records.

Their activities are related to administration, education, health care service, judicial system, culture, economy, banking, social protection, socio-political organization and various forms of association. Also, 1,140 institutions, organizations and enterprises that have discontinued their operations due to receiverships, liquidation, merger or other forms of ownership transformations. In addition to supervision, the Service for the protection of the records outside the archives offers consulting service to the creators of the archives.

The service consists of monitoring the legislation, interpretation of the provisions and consultations with corresponding persons and registry offices. Assistance to registry offices is reflected in the possibilities to use instructions, regulations and model disposition lists. They have been made by the professional service of the Archives with the intention of realizing optimum preliminary preservation of the records in the field.