ICO anonymisation guidance: the motivated intruder test (Information Commissioner's Office, Anonymisation guidance, 'How do we ensure anonymisation is effective?', 28 March 2025)
A holder can test its de-identified lot by asking what a motivated person with reasonable means could do to identify someone. The result goes into the file that proves the lot is anonymous or de-identified.
Dated 18 Oct 2026Source checked 18 Oct 2026Basis: primary text
In the source's own words
“Applying a "motivated intruder" test is a good starting point to consider identifiability risk.”
Where it was read
Also read from the same source
- ICO anonymisation guidance: the same information can be personal data for one party and anonymous for another (Information Commissioner's Office, Anonymisation guidance, 'How do we ensure anonymisation is effective?', 28 March 2025 (under review after the Data (Use and Access) Act))
- Details that identify together are coarsened and measured
- A person reads records picked at random
- An independent provider tests and certifies before each transfer
Figures it counts in
It is shown on its own, not counted into a figure.
Cited in this guide