What evidence do auditors commonly ask for on A.3.29 Secure system architecture and engineering principles?

Engineering principles referencing privacy by design and by default; Design evidence that systems can enforce purpose limitation, retention and deletion; Architecture reviews of PII-processing systems against the principles.

What is the most common gap auditors find on A.3.29?

Systems that cannot delete an individual's data without a database engineer

ISO/IEC 27701:2025 · Annex A Table A.3 information security controls with PII-specific guidance

`A.3.29` Secure system architecture and engineering principles

Any system or component that processes PII shall be engineered on privacy by design and by default principles, built so that the relevant Annex A controls for controllers and processors are easy to anticipate and put in place, and above all so that it gathers and handles only the PII needed for the purposes already identified. As an illustration, where PII has to be removed after a set period, the system shall be built to make that removal straightforward.

Source: ISO/IEC 27701:2025, A.3.29. The statement above is our statement of the clause, read from the published text and cited so you can check it against the official text, not the instrument verbatim. Open ISO/IEC 27701:2025 in the compliance library.

artefacts

held by a system

at each review

hard

to go live

Cloud console / configuration management

where the evidence lives

teal = a system already holds it · olive = produced at each review. To go live: easy when half or more of the artefacts are already held by a system, moderate from a quarter to a half, hard below a quarter.

These are the artefacts auditors commonly ask for on this requirement, our guidance rather than text from the standard. Your assessor decides what is sufficient in your context, and asks for samples across the period when a report covers one.

system holds itEvidence a system already holds

none for this control

periodic reviewEvidence produced at each review

Design evidence that systems can enforce purpose limitation, retention and deletion · Cloud console / configuration management
Architecture reviews of PII-processing systems against the principles · Cloud console / configuration management

governing documentDocuments that govern the control

Engineering principles referencing privacy by design and by default · Policy repository / GRC workspace

First move

No system holds this evidence for you: it is people and documents. Reminders and routing to the owner still save time. Put the document under version control with an owner and review date, and log each review as a record with reviewer and date.

Common gaps auditors find

Systems that cannot delete an individual's data without a database engineer
Data models that collect fields no purpose requires

Do this for your whole sheet

Paste the rows you run your controls from and get this mapping for every control at once, with the periodic-review ones flagged and a first move per row. No account for the first run.

Build my evidence sheet

A.3.28 Application security requirements · A.3.30 Outsourced development