Substantial modification

A modification to a high-risk AI system that, under Article 25(1) of Regulation (EU) 2024/1689, triggers reclassification of a deployer as a provider because the modification materially affects the system's intended purpose, performance, or risk profile and requires a new conformity assessment and a new EU declaration of conformity. A key criterion is that the modification was not foreseen or planned in the initial conformity assessment: planned adaptive behaviour that was within the original intended purpose and anticipated in the original technical documentation and risk assessment does not automatically trigger reclassification. This distinction matters in practice: providers should document, in the initial conformity assessment, the range of anticipated modifications and updates that fall within the system's planned lifecycle, so that later changes within that documented range can be distinguished from genuinely new modifications that change the system's scope or risk profile.

A change to a high-risk system significant enough that, under Article 43(4), it must undergo a new conformity assessment. Retraining on a new population or changing what triggers a decision can qualify, which is why the file logs every version and change with dates.

A change to an AI system after it is placed on the market that is not foreseen in the initial conformity assessment and affects its compliance or intended purpose (Article 3(23)); the trigger that sends a classification memo back for review (the "next review upon substantial modification" line).

A change to an AI system after its placing on the market or putting into service which is not foreseen or planned in the initial conformity assessment by the provider and which affects the compliance of the AI system with the requirements of the Act, or results in a change to the intended purpose. Triggers reclassification review. (Art. 3(23))

A change to an AI system after its placing on the market or putting into service that (a) is not foreseen or planned in the initial conformity assessment and (b) affects compliance with Chapter III Section 2 requirements or results in a change to the assessed intended purpose. Triggers Article 25(1)(b) provider-status transfer. Operational default: if a party cannot access the original conformity assessment and therefore cannot determine whether a change was "foreseen or planned," the safe operational position is to treat the trigger as fired until access to the conformity assessment proves otherwise. An unresolvable trigger is not a safe trigger. (Article 3(23), Regulation (EU) 2024/1689)