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Substantial modification

By Updated

Under the EU AI Act, a change after placing on the market that the initial conformity assessment did not foresee and that affects compliance or changes the intended purpose 1. It triggers a new conformity assessment and can turn a deployer or distributor into the provider; pre-determined changes are exempt.

Developed in
ch. 18, Article 25: when someone else becomes the provider
ch. 14, Substantial modification
ch. 15, When a deployer becomes a provider
Chapters
ch. 14, Development · ch. 15, Deployment · ch. 18, EU AI Act
Contrast with
Pre-determined changes
Source
1 numbered reference, listed below

Where it is used

8 chapters of the Body of Knowledge use the term. Each link opens the first section that does.

  • Downstream modifier (GPAI)

    An actor that fine-tunes or modifies another provider's general-purpose AI model.

  • Conformity assessment

    The procedure by which a provider shows a high-risk AI system meets the EU AI Act before placing it on the market: internal control for most Annex III…

  • Placing on the market

    Under the EU AI Act, the first making available of an AI system or general-purpose AI model on the Union market; later supplies in the course of a commercial…

  • Intended purpose

    The use for which the provider intends an AI system, including its specific context and conditions of use.

  • AI Act (EU)

    Regulation (EU) 2024/1689, the EU's horizontal, risk-tiered law for AI, amended by the Digital Omnibus.

  • Distributor

    Under the EU AI Act, a person in the supply chain, other than the provider or the importer, who makes an AI system available on the Union market.

  • Deployer

    Under the EU AI Act, whoever uses an AI system under its own authority, other than in a purely personal, non-professional activity.

Sources

  1. [1] Regulation (EU) 2024/1689 (AI Act), consolidated text as amended by Regulation (EU) 2026/1744 (Digital Omnibus on AI, in force 27 Jul 2026; definitions in Art. 3, incl. 3(1), 3(3) to 3(14), 3(14b), 3(20), 3(22), 3(23), 3(29) to 3(32), 3(49), 3(55) to 3(57), 3(60), 3(61), 3(63), 3(68); Arts. 4, 5, 6 (incl. 6(3) third subparagraph, profiling), 9, 10, 11, 13, 14, 15, 17, 22 to 27 (incl. 26(11)), 40, 41, 43, 47, 48, 50, 53 (incl. 53(1)(c)), 55, 57, 60, 72, 73, 86; Annexes I, III, IV). Publications Office of the EU (EUR-Lex). 2026-07-27. https://eur-lex.europa.eu/eli/reg/2024/1689/2026-07-27/eng (verified: primary)

Definitions of legal terms paraphrase the cited text, which governs. Dated statements are as of .

Cite this term

García Aibar, J. (2026). Substantial modification. In AI Governance Engineering: The Thesis & Body of Knowledge (v0.5.0), Glossary. https://doi.org/10.5281/zenodo.22956197. https://aigovernanceengineer.com/glossary/substantial-modification. CC BY 4.0

BibTeX

@misc{aige2026substantialmodification,
  author  = {Jorge García Aibar},
  title   = {{Substantial modification}},
  note    = {Glossary, AI Governance Engineering: The Thesis \& Body of Knowledge, version 0.5.0},
  year    = {2026},
  doi     = {10.5281/zenodo.22956197},
  url     = {https://aigovernanceengineer.com/glossary/substantial-modification}
}