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What Is the Online Safety Act 2023? A Simple Guide

Published 9 July 2026

The Online Safety Act 2023 is the most significant reform of UK internet law in over twenty years. It does two things simultaneously: it imposes legal duties of care on every platform where users interact — from Twitter to comment sections to gaming chat — and it creates four new criminal offences for harmful online behaviour, with maximum sentences of up to 5 years. It also gives OFCOM, the communications regulator, enforcement powers that escalate from polite requests to court orders blocking platforms from operating in the UK entirely.

This guide explains what the Act covers, who it affects, and what it means for both platforms and the people who post on them.

Disclaimer: This is general information, not legal advice. The OSA is a complex statute with detailed codes of practice. If your platform falls within its scope, speak to a solicitor specialising in tech regulation.

Jurisdiction: The OSA applies UK-wide. This article focuses on England and Wales.

The Online Safety Act 2023: Two Systems, One Act PART 3: PLATFORM DUTIES Illegal content risk assessments (s.9) Children's safety duties (ss.11-13) Proportionate safety measures (s.10) Enforced by OFCOM PART 10: NEW CRIMINAL OFFENCES s.179 False communications (6 months) s.181 Threatening communications (5 years) s.183 Epilepsy trolling (5 years) Enforced by Police + CPS OFCOM enforcement ladder: Information request → Notice → Fine (up to £18m/10% turnover) → Business disruption → Blocking Steps 1-3 active. Steps 4-5 not yet used. Key dates: Royal Assent Oct 2023 → Part 10 offences in force 31 Jan 2024 → Platform duties from 10 Mar 2025 Sources: Online Safety Act 2023; OFCOM online safety codes
The OSA operates on two levels: platform duties (enforced by OFCOM) and individual criminal offences (enforced by police and CPS).

Part 3: What Platforms Must Now Do

The OSA applies to any "user-to-user service" with links to the UK — social media, forums, comment sections, messaging apps, dating sites, gaming platforms with chat. If users can encounter content generated by other users, the duties likely apply.

Every in-scope platform must carry out an illegal content risk assessment (s.9) identifying how likely users are to encounter priority illegal content — terrorism, child exploitation, threats to kill, and other serious categories. Once assessed, the platform must take proportionate measures (s.10) to mitigate those risks. Platforms likely to be accessed by children must carry out a separate children's risk assessment (s.11) covering content harmful to children — including suicide, self-harm, and eating-disorder content — even if it's not illegal. Age verification or estimation is explicitly contemplated.

Category 1 services — the largest platforms designated by OFCOM — face additional duties, including protecting adults from certain harmful content and giving users tools to control what they see. Section 19 requires platforms to have "particular regard" to users' freedom of expression and privacy when implementing safety measures.

Part 10: The Four New Criminal Offences

The OSA created four new criminal offences, all in force from 31 January 2024. They replaced the old s.127(2) false messages offence and created named offences for specific types of online harm that older statutes covered poorly or not at all:

s.179 — False Communications (6 months): Knowingly sending false information with intent to cause non-trivial psychological or physical harm. Replaces the old "annoyance or inconvenience" standard with a meaningful harm threshold. Both knowledge of falsity AND intent to cause harm must be proved.

s.181 — Threatening Communications (5 years): Conveying a threat of death or serious harm, intending or being reckless as to whether the recipient fears it. Either-way. The most serious individual-speech offence short of the hatred provisions.

s.183 — Epilepsy Trolling (5 years): Sending flashing images with intent to induce a seizure in someone with epilepsy, or recklessness. No actual seizure needs to have occurred.

s.184 — Encouraging Self-Harm (5 years): Encouraging or assisting serious self-harm — harm amounting to grievous bodily harm. Intent or recklessness. Statutory defence for communications genuinely intended to prevent or reduce self-harm.

OSA Part 10 vs Older Offences: What Changed s.127(2) Comms Act "Annoyance or inconvenience" REPEALED → s.179 OSA 2023 "Non-trivial psychological or physical harm" → HIGHER BAR Knowledge + intent + genuine harm required s.127(1) (grossly offensive messages) remains in force — the OSA only repealed s.127(2) (false messages) s.127(1) continues alongside the new OSA offences for general offensive content Also relevant: C&P Act 2026, s.250 expands corporate liability for senior managers obstructing OFCOM
What the OSA replaced and what it kept. The old "annoyance or inconvenience" standard is gone — replaced by a genuine harm threshold.

How the OSA Fits With Other Laws

Communications Act 2003, s.127: The OSA repealed s.127(2) (false messages) but left s.127(1) (grossly offensive messages) intact. For general offensive content, s.127 remains the primary charge. For knowing falsehoods causing specific harm, s.179 applies. For threats, s.181 applies.

Human Rights Act 1998, Article 10: The free-expression safeguard. Section 19 of the OSA requires platforms to consider users' Article 10 rights when implementing safety measures. Category 1 services must give adult users tools to control what they see — effectively an opt-in for more content rather than blanket removal.

Crime and Policing Act 2026, s.250: From 29 June 2026, senior managers who obstruct OFCOM investigations face criminal liability — and their companies can be prosecuted too. This bridges the gap between the platform duties (OFCOM enforcement) and individual criminal offences (police and CPS).

Practical Takeaways Two systems, one Act Platform duties + individual offences operate together OFCOM has real teeth Fines up to 10% global turnover. Active enforcement. Free expression protected s.19 requires regard to Article 10 rights Most significant UK internet law reform in 20+ years. Both platforms and individuals affected. Platform duties from Mar 2025. Criminal offences from Jan 2024. OFCOM enforcement active.
The OSA is a landmark statute — two systems operating together, enforced by two different regulators, affecting both platforms and individuals.

Sources

UK Content Comply analyses content against 13 UK speech law frameworks. For full coverage of every framework, see our UK Speech Law resources.