The new version of the Merchandise Registration Notification (NIM) guide is published in the declarant's records. Testing can be done in the PREproduction environment from 01/15/2024. In PROduction it will be on 01/07/2024.

See in Headquarters of the AEAT the document " Technical Guide for Notification of Registration of Goods V 0.4 " Tax Agency: Technical guides - Notification System for Registration of goods by holders of registration ...  

Due to this, and due to its relationship with the import declaration adapted to the Customs Code of the Union, it has been modified to allow the declaration of Merchandise Registration Notification (NIM). To do this, it is recommended to look at the AEAT Headquarters in the document: " Additional Import Information CAU V3.4" section "Separate 1. Previous Document. Box 1201. " where the special case of the declaration of the NIM document (Notification of Registration of Merchandise) is explained

Tax Agency: Technical guides - Presentation SAD (Single Administrative Document)

Note; The calendar has no variation. It can be consulted in the new feature published on 06/21/2023: https://sede.agenciatributaria.gob.es/Sede/en_gb/aduanas/novedades/2023/Declaraciones_de_importacion_CAU_y_notificacion_previa_al_despacho.html