Data minimisation is a core principle of the GDPR and of most modern privacy law: collect and retain only what is strictly necessary for your purpose. In age verification, the purpose is usually to establish that a user meets a minimum age (e.g. 18+). You do not need their name, full birth date, address, or a copy of their ID for that; you need a reliable "yes" or "no" and, for compliance, evidence that the check was performed.
What you actually need to keep
You typically need only a signed outcome (e.g. "18+ verified" or "under 18") and an audit identifier (e.g. a verification receipt) so you can demonstrate compliance to a regulator. That is enough for day-to-day access control. You do not need to store the ID image, the selfie, or a reversible biometric template.
What you should never store
Avoid storing scans of passports or driver’s licences, face images, or any identifier that could be used to re-identify the person beyond the verification event. The more you store, the bigger the breach risk and the harder it is to justify under data minimisation. Regulators and courts have pushed back on age verification that creates large, centralised identity databases.
How privacy-first verification helps
A well-designed provider checks the document and the person, then discards the raw inputs (or keeps only a non-reversible representation for reverification). It returns to you only the outcome and an audit ID. You never see or store the ID or face. Your systems stay minimal, and your story to users and regulators stays simple: you only keep what you need to show that you verified age.
