ChatGPT and your client data: why UK SMBs are switching to Microsoft Copilot Chat

Yes, staff pasting client data into the free version of ChatGPT is a real risk for UK SMBs, and the safer alternative is Microsoft Copilot Chat. It is included at no extra cost with Microsoft 365 Business Standard, Business Premium and the equivalent enterprise plans, and it keeps prompts inside your Microsoft tenant boundary.

The most common AI security incident in UK SMBs in 2026 is not a clever attack. It is a junior fee-earner pasting a client contract into free ChatGPT to “tidy it up”, and the contents ending up on a server outside the firm’s control. Lanmark is a Microsoft Direct Cloud Solution Provider. This guide explains the risk, the structural difference between ChatGPT and Copilot Chat, and the steps to take in the next four weeks.

The risk most firms have not seen yet

The conversation in most SMBs has moved from “should we allow AI” to “what is everyone already using”. The answer, almost always, is ChatGPT on the free tier, signed in with a personal Google or Microsoft account, on a corporate laptop. Staff are not being reckless. They are being useful: drafting client emails faster, summarising long documents and producing first drafts they would otherwise write on a Sunday evening.

The problem is that everything they paste leaves the firm’s compliance boundary. On consumer ChatGPT, the default is that prompts and responses can be retained by the provider and used for model training. The user can disable this in settings; most do not. Without an enterprise account, the firm has no audit log of what was sent, no data residency commitment, no contractual processor relationship and no ability to delete data on request. For a UK firm subject to UK GDPR, the SRA Code of Conduct, FCA conduct rules or client confidentiality clauses, this is a recurring data processing incident hiding in plain sight.

The ICO’s guidance on AI and data protection is clear that processing personal data through a generative AI service without a lawful basis, appropriate contracts and a risk assessment is unlikely to meet a firm’s UK GDPR obligations.

Why ChatGPT is the wrong place for confidential SMB work

Three structural issues make consumer ChatGPT the wrong tool for client work.

• Data residency. Consumer ChatGPT processes prompts on infrastructure that may sit outside the UK and EU, with no commitment about where a specific firm’s prompts are processed. For a regulated UK SMB, that is the first conversation that fails an audit.
• Processor relationship. A firm using consumer ChatGPT has accepted a personal terms of service, not a data processing agreement. When an auditor, regulator or client asks who is processing this data and under what contract, there is no answer.
• Observability. The firm cannot see what staff are sending. Defender for Cloud Apps and similar tools can flag traffic to chat.openai.com but cannot inspect every prompt. The firm is relying on staff judgement applied at speed against a deadline.

The result is a workflow that is genuinely useful for staff and genuinely unmanageable for the firm.

How Microsoft Copilot Chat is structurally different

Microsoft Copilot Chat is the free generative AI chat experience available to any user with a Microsoft Entra ID work account. It differs from consumer ChatGPT in four ways:

• Prompts and responses are processed inside the Microsoft commercial data boundary. UK data residency is available, and Microsoft does not use this data to train its public foundation models.
• A signed-in work account ties every interaction to a named user and your audit logs. Microsoft Purview, Entra ID logs and Defender for Cloud Apps capture who used Copilot Chat, when and at what scale.
• The terms are commercial Microsoft terms covering your tenant, not a consumer agreement. For most SMBs already paying for Microsoft 365, the data processing relationship is already in place.
• Copilot Chat does not access internal SharePoint, OneDrive or Teams content by default. That is what the paid Microsoft 365 Copilot Business tier adds.

If the immediate need is “stop staff using ChatGPT”, free Copilot Chat is enough. Copilot Business is the next step when you want the AI to reach across your own data. See Microsoft 365 Copilot Business for UK SMBs.

A practical four-week switch plan

• Week one: acceptable-use update. Publish a short, plain-English policy: confidential client and personal data goes into Copilot Chat only, never into consumer AI tools. Pair it with a screenshot showing staff where Copilot Chat sits in the Microsoft 365 launcher.
• Week two: enablement. Configure Conditional Access, browser-side restrictions and DNS-level controls to block consumer ChatGPT and similar services on corporate devices and networks. Where Edge is the standard browser, pin the Copilot Chat button. Run a 45-minute lunchtime training session per team showing three or four day-to-day prompts that work well.
• Week three: monitoring. Review Defender for Cloud Apps and Entra ID logs to confirm that traffic to consumer AI services has dropped and Copilot Chat usage is rising. Capture legitimate workflow needs Copilot Chat does not cover, rather than letting staff drift back to ChatGPT.
• Week four: governance. Review sensitivity labels across SharePoint and OneDrive, add “AI data exposure” as a category in your incident response runbook, and book a 90-day review to assess readiness for Copilot Business.

For data that has already left the firm, the practical remedy is a written record of the categories exposed, a risk assessment, deletion requests to the provider where possible and a note in your processing log. The ICO’s expectation is that firms take reasonable steps and document them.

Where Lanmark fits

Lanmark is a Microsoft Direct CSP, so licensing and support for Copilot Chat and any later move to Copilot Business sit with one provider. Around the Microsoft platform sits our managed detection and response service, a 24x7 SOC, and our wider cyber security work. The NCSC guidance on AI security principles is the reference framework we work to.

See our AI consultancy and generative AI consultancy pages, or contact us to plan the switch.