AI Governance Engineer
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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.

Substantial modification: mentions per chapter20 mentions of the term across 8 of the 23 chapters of the Body of Knowledge; the chapters the glossary cross-references are drawn solid.Cross-referenced chapterOther chapter08 Regulatory Map: 4 mentions08 Regulatory Map414 Development: 4 mentions14 Development415 Deployment: 4 mentions15 Deployment418 EU AI Act: 3 mentions18 EU AI Act320 Existing Law: 2 mentions20 Existing Law221 AI Laws Worldwide: 1 mention21 AI Laws Worldwide122 Principles & Standards: 1 mention22 Principles & Standards123 AI Agents: 1 mention23 AI Agents1No mentions in the other 15 chaptersSource: the Body of Knowledgev0.5.0
Substantial modification: mentions per chapter20 mentions of the term across 8 of the 23 chapters of the Body of Knowledge; the chapters the glossary cross-references are drawn solid.Cross-referenced chapterOther chapter000102030405060708 Regulatory Map: 4 mentions4081011121314 Development: 4 mentions41415 Deployment: 4 mentions415161718 EU AI Act: 3 mentions3181920 Existing Law: 2 mentions22021 AI Laws Worldwide: 1 mention12122 Principles & Standards: 1 mention12223 AI Agents: 1 mention123Source: the Body of Knowledge v0.5.0
Mentions per chapter How often each chapter names the term, with the chapters the glossary cross-references drawn solid. The longest bar is where to read the term in use; bars spread across many chapters mark a term that runs through the discipline.
Mentions as a table
Mentions of Substantial modification per chapter
ChapterMentionsCross-referenced
00 Preface0No
01 Definition0No
02 Why Now0No
03 Values & Principles0No
04 The Stack0No
05 Patterns0No
06 The Role0No
07 Maturity Model0No
08 Regulatory Map4No
10 Reading List0No
11 AI Defined0No
12 Governance Program0No
13 Risk Management0No
14 Development4Yes
15 Deployment4Yes
16 Fairness & XAI0No
17 Incidents0No
18 EU AI Act3Yes
19 Privacy & AI0No
20 Existing Law2No
21 AI Laws Worldwide1No
22 Principles & Standards1No
23 AI Agents1No
Substantial modification: related terms and patternsThe term at the centre; related terms on solid edges, the terms it is contrasted with on dashed edges, and the patterns that use it most in the colour of their layer.RelatedContrastSubstantial modificationRelated terms (7)AI Act (EU) · RelatedAI Act (EU)Conformity assessment · RelatedConformity assessmentDeployer · RelatedDeployerDistributor · RelatedDistributorDownstream modifier (GPAI) · RelatedDownstream modifier (GPAI)Intended purpose · RelatedIntended purposePlacing on the market · RelatedPlacing on the marketContrast with (1)Pre-determined changes · ContrastPre-determined changes
Substantial modification: related terms and patternsThe term at the centre; related terms on solid edges, the terms it is contrasted with on dashed edges, and the patterns that use it most in the colour of their layer.RelatedContrastRelated terms (7)AI Act (EU) · RelatedAI Act (EU)Conformity assessment · RelatedConformity assessmentDeployer · RelatedDeployerDistributor · RelatedDistributorDownstream modifier (GPAI) · RelatedDownstream modifier (GPAI)Intended purpose · RelatedIntended purposePlacing on the market · RelatedPlacing on the marketContrast with (1)Pre-determined changes · ContrastPre-determined changesSubstantialmodification
The term's neighbourhood Terms related to this one on solid edges, terms it is often confused with on dashed edges, and the patterns that use it most in the colour of their layer. Follow a dashed edge to check the distinction before you use either term.
Neighbourhood as a table
Neighbourhood of Substantial modification
FamilyItemRelation
Related termsAI Act (EU)Related
Related termsConformity assessmentRelated
Related termsDeployerRelated
Related termsDistributorRelated
Related termsDownstream modifier (GPAI)Related
Related termsIntended purposeRelated
Related termsPlacing on the marketRelated
Contrast withPre-determined changesContrast
  • 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}
}