This Practice Note provides practical guidance on the duties under Part 5 of the Online Safety Act 2023 (OSA 2023) that apply to online service providers (eg platforms) that display or publish pornographic content. These duties primarily revolve around age assurance measures, as they require such providers to: • implement highly effective age assurance measures to ensure children cannot access such services • keep written records of the measures implemented, and • summarise the written records in a publicly available statement This Practice Note explores which services are in scope, what the duties entail and how relevant providers may comply, with reference to Ofcom’s Guidance on highly effective age assurance and other Part 5 duties. Ofcom has a statutory duty under OSA 2023, s 82 to produce such guidance in order to assist service providers in complying with their duties under OSA 2023, ss 79–82 (Part 5). The services regulated under OSA 2023, Part 5 are those that display or publish pornographic content that is not user-generated (ie it