Artifact GuideUKCategorisation

UK Online Safety Act Categorisation

Q: What are the Category 1, 2A, and 2B thresholds?

Category 1 applies where a regulated user-to-user service exceeds 34 million average monthly active UK users and uses a content recommender system, or exceeds 7 million average monthly active UK users and has both a content recommender system and functionality for users to forward or share regulated user-generated content with other users. Category 2A applies where a regulated search service, or the search engine of a combined service, exceeds 7 million average monthly active UK users and is not the specified type of vertical search engine limited to selected sites or databases under a relevant arrangement. Category 2B applies where a regulated user-to-user service exceeds 3 million average monthly active UK users and provides qualifying direct messaging designed so messages cannot be encountered by other users unless the sender or recipient takes further action. Apply each threshold to the relevant user-to-user part or search engine, not automatically to every function of a combined service. Use the Regulations' monthly-active-UK-user calculation and prescribed assessment period rather than a global account count or headline reach figure. Document the recommender, forwarding or sharing, search, and direct-messaging functionality with product evidence.

Categorisation adds duties to specified high-reach or high-functionality Part 3 services. It does not decide whether the baseline Online Safety Act applies.

This guide explains the statutory thresholds, Ofcom's register, combined services, and the evidence needed to monitor category status.

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Author

Sorena AI

Published

May 9, 2026

Updated

Jul 25, 2026

Questions

Structured answer sets in this page tree.

Primary sources

Cited legal and guidance references.

Publication metadata

Sorena AI

Published May 9, 2026

Updated Jul 25, 2026

Overview

A regulated Part 3 service can have illegal-content and child-safety duties without being categorised. applies to qualifying user-to-user services, to qualifying search engines, and to qualifying direct-messaging services. Formal category status is shown in Ofcom's published register.

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Question 1

What are the Category 1, 2A, and 2B thresholds?

applies where a regulated user-to-user service exceeds 34 million average monthly active UK users and uses a content recommender system, or exceeds 7 million average monthly active UK users and has both a content recommender system and functionality for users to forward or share regulated user-generated content with other users.

applies where a regulated search service, or the search engine of a combined service, exceeds 7 million average monthly active UK users and is not the specified type of vertical search engine limited to selected sites or databases under a relevant arrangement.

applies where a regulated user-to-user service exceeds 3 million average monthly active UK users and provides qualifying direct messaging designed so messages cannot be encountered by other users unless the sender or recipient takes further action.

Apply each threshold to the relevant user-to-user part or search engine, not automatically to every function of a combined service.
Use the Regulations' monthly-active-UK-user calculation and prescribed assessment period rather than a global account count or headline reach figure.
Document the recommender, forwarding or sharing, search, and direct-messaging functionality with product evidence.

Citations

Online Safety Act 2023 (Category 1, Category 2A and Category 2B Threshold Conditions) Regulations 2025

Binding thresholds, functionality conditions, definitions, and user-number calculation rules.

Ofcom - Register of categorised services

Restates the thresholds and identifies services placed on the register.

Question 2

How does a service become formally categorised?

An internal threshold calculation is a monitoring decision, not the formal categorisation result. Ofcom assesses services, gives affected providers an opportunity to make representations, and publishes the register required by section 95. The register was published on 10 July 2026.

A service can appear in more than one category, and only the relevant part may be categorised. Ofcom's register, for example, explains that category treatment of a search function within a combined service does not automatically extend to non-search chatbot or feed functionality.

Check the current Ofcom register and retain the entry, provider entity, service description, category, and effective review date.
Notify the responsible legal and product teams of a provisional assessment or information request and preserve the underlying metrics.
Monitor material changes in UK users and qualifying functionality even when the service is not currently on the register.

Citations

Ofcom - Register of categorised services

Current register, category explanations, service-part qualifications, and Ofcom process.

Online Safety Act 2023, sections 95 and 96

Requires Ofcom to establish and maintain the register of Category 1, 2A, and 2B services.

Question 3

What changes after categorisation?

All three categories are subject to transparency reporting after an Ofcom notice. services also face additional user-empowerment, content, terms, and fraudulent-advertising duties; services have additional search and fraudulent-advertising duties; services have additional transparency obligations. The exact commencement and applicable notice must be checked for each duty.

and providers must also publish specified risk-assessment findings and provide Ofcom with assessment records as required. Categorisation does not replace the baseline illegal-content, children's access, child-safety, complaints, record-keeping, or enforcement duties.

Build a duty map by category, service part, commencement status, and regulator notice.
Keep risk-assessment publication text consistent with the full internal record while protecting information the law does not require to be disclosed.
Do not delay baseline duties while waiting for categorisation.

Citations

Ofcom - Register of categorised services

Explains the additional responsibilities attached to the categorised-services regime.

Online Safety Act 2023

Creates the annual transparency-notice framework for providers of relevant, categorised services.

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