---
title: "Substantial modification"
description: "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."
canonical: https://aigovernanceengineer.com/glossary/substantial-modification
author: "Jorge García Aibar"
license: "CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)"
doi: https://doi.org/10.5281/zenodo.22956197
version: "0.5.0"
updated: 2026-09-25
---

# Substantial modification

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](https://aigovernanceengineer.com/bok/eu-ai-act#article-25-when-someone-else-becomes-the-provider); [ch. 14, Substantial modification](https://aigovernanceengineer.com/bok/governing-development#substantial-modification); [ch. 15, When a deployer becomes a provider](https://aigovernanceengineer.com/bok/governing-deployment#when-a-deployer-becomes-a-provider)
- Chapters: [ch. 14, Development](https://aigovernanceengineer.com/bok/governing-development) · [ch. 15, Deployment](https://aigovernanceengineer.com/bok/governing-deployment) · [ch. 18, EU AI Act](https://aigovernanceengineer.com/bok/eu-ai-act)
- Contrast with: [Pre-determined changes](https://aigovernanceengineer.com/glossary/pre-determined-changes)
- In the glossary chapter: https://aigovernanceengineer.com/bok/glossary#t-substantial-modification

## Sources

[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)