What is an AI system inventory?
An AI system inventory is a register of every AI model, agent and third-party AI service an organisation builds or uses, with its purpose, data, owner and risk class. ISO 42001 and the EU AI Act both start from it, because you cannot assess or govern a system you have not listed.
What goes in it
Each entry describes one system well enough that someone outside the team could understand what it does and why it matters. Link each entry to its impact assessment, to its risks in the risk register, and to the suppliers involved.
- Identity. Name, version, a short description, and whether you built it, bought it or call it through an API.
- Purpose. What it is used for, which decisions it informs, and who uses it.
- Data. Training, input and output data, and whether any of it is personal or confidential.
- Owner. A named person accountable for the system and for keeping its entry current.
- Classification. Your internal risk tier and, where the EU AI Act applies, its risk category and your role as provider or deployer.
Why everything starts from it
ISO 42001 has no clause titled “inventory”, but its scope (clause 4.3), AI risk assessment (6.1.2) and AI system impact assessment (6.1.4) all depend on knowing which systems are in play. Its Annex A also asks for the resources behind each system, such as data, tooling and computing, to be documented.
The EU AI Act sets obligations by role and risk category: banned practices under Article 5, high-risk systems under Article 6 and Annex III, and transparency duties under Article 50. Each system has to be classified before you know which apply. The NIST AI RMF asks for the same thing in Govern 1.6, which calls for mechanisms to inventory AI systems.
Finding what is in use
Models your own team built are easy to list. The gaps are usually AI features switched on inside existing SaaS tools, AI APIs called from code, and tools staff signed up to on their own. Procurement and expense records, supplier reviews, the list of apps in your single sign-on, a search of code for AI libraries and keys, and a short survey of each team will find most of them.
To keep the inventory current, make adding an entry part of procurement and change approval, and check it in full at planned intervals, such as before each management review.
Questions
AI system inventory, answered
Does a third-party AI tool belong in the inventory?
Yes. If staff or systems use it with company data, it belongs there. Under the EU AI Act you are usually a deployer of such a tool, and under ISO 42001 AI you use is in scope as well as AI you build.
Is a spreadsheet good enough?
For a first version, yes, if it has the fields an auditor will ask about, a named owner per entry and a review date. It gets harder to keep current once impact assessments, risks and suppliers need linking to each entry.
Who should own it?
One person should own the inventory as a whole, often the AI governance or compliance lead. Each entry also needs its own owner, usually the person responsible for that system or supplier.
Working through this for an audit?
Talk it through with someone who has run the audit before, or look up another term.
- Each customer workspace has its own database
- Every change written to a tamper-evident activity log
- Auditors get scoped, read-only access
- AI suggestions wait for a person to accept them