Substack has begun requiring age verification for users in the United Kingdom, adopting new checks to comply with obligations set out in the UK’s Online Safety Act.

The move means that readers attempting to access content flagged as potentially harmful or adult-oriented may now be prompted to confirm their age through an ID-based process before being allowed to view certain posts or interactive features.

Under the new rules, UK-based users may be asked to upload a government-issued document or complete a selfie-matching step through an external verification service.

Once confirmed, users regain full access to material that would otherwise be restricted.

Substack emphasised that the introduction of age-gating reflects legal requirements rather than any shift in its editorial policies, and that content not classified as restricted remains freely accessible without verification.

Those unwilling to provide identification can still browse Substack, though some newsletters, chats, livestreams and community tools may appear blurred or remain inaccessible.

The company acknowledged concerns regarding privacy but stated that compliance with the law is necessary to continue operating in the UK while providing safe access for adult users.

The change places Substack among a growing group of digital platforms updating their systems in response to the Online Safety Act’s enforcement.

As regulators continue clarifying how broadly restricted content should be interpreted, discussions around privacy, data handling and the scope of age checks are expected to intensify.