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Copilot Updates · 4 min read

GPT-5.6 Arrives in Microsoft 365 Copilot: What It Changes for UK Businesses

By James Wilkinson 12 July 2026

GPT-5.6 is rolling out across Microsoft 365 Copilot including Cowork. What it changes about model choice for firms that keep client work inside Microsoft.

TL;DR
  • GPT-5.6 is rolling out across Word, Excel, PowerPoint, Copilot Chat and Copilot Cowork, and Microsoft is calling it the preferred model for Copilot.
  • Until now the strongest models for heavy multi-step work in Copilot have been Anthropic's Claude models, which UK tenants must switch on deliberately.
  • GPT-5.6 runs entirely inside Microsoft's environment. Businesses that ruled out Claude on data grounds now get a frontier option with nothing to enable.

Microsoft has started rolling out OpenAI’s new GPT-5.6 model across Microsoft 365 Copilot. In plain terms, the AI behind Copilot in Word, Excel, PowerPoint, Copilot Chat and Copilot Cowork has just taken a significant step up, and Microsoft is describing GPT-5.6 as the preferred model for Copilot.

Most businesses will not need to change anything to get it. It arrives on its own, tenant by tenant. But there is a decision buried inside this release that is worth understanding properly, especially if your firm handles sensitive client data.

A quick reminder: Copilot is not one model

Copilot does not run on a single AI model. Behind the scenes, Microsoft offers a choice between models from OpenAI, the company behind ChatGPT, and Anthropic, the company behind Claude. We covered how that stack fits together in more technical detail, but the short version is that an orchestrator decides which model answers you, and a picker lets you override it.

In our training work, the pattern we see most often is that teams get better results from the Claude models on the heavier tasks. Complex Excel analysis is one example. Copilot Cowork is another, the newer part of Copilot where you describe the outcome you need and it goes away and produces the finished piece of work.

The catch with Claude

Using Claude inside Copilot is not automatic. An administrator has to switch Anthropic models on, and that switch carries a data question. Claude runs on Anthropic’s systems rather than Microsoft’s. The usage is covered by Microsoft’s data protection terms, but the processing happens outside Microsoft’s own environment, and for UK tenants the setting ships switched off.

Plenty of firms have looked at that properly and enabled it. Others have decided their client commitments or regulatory position mean everything stays inside Microsoft, full stop. Both are defensible positions, and we set out how to think about the decision in our guide to using Copilot with client data. The frustration for the second group has been simple: saying no to Claude has meant missing the strongest models for the most useful parts of Copilot.

Why GPT-5.6 changes the calculation

GPT-5.6 is built for exactly that heavy, multi-step work, and it runs entirely inside Microsoft’s environment. There are no settings to change and no data decision to make. It sits under the standard Copilot commitments your tenant already operates under.

That matters in two directions.

If your firm said no to Claude, you are no longer locked out of frontier capability in the places it counts, including Cowork. The gap between what cautious tenants and permissive tenants can do has just narrowed considerably.

If your firm said yes to Claude, you now have two strong options rather than one. Leave the model choice on Auto and Copilot will usually route the task sensibly. Where the model selector is available you can also choose GPT-5.6 directly, and the judgement about when switching is worth it has not changed since we wrote our guide to the Copilot model picker. The model names move faster than the advice does.

Microsoft’s own models are arriving quietly

Worth knowing alongside this: Microsoft is building its own models, and some are already doing quiet work inside PowerPoint and Teams. Nobody announces these with a keynote. The direction of travel is clear though. More model choice, with more of it running inside Microsoft’s own environment.

What to do this week

Pick two real tasks your team repeats. A monthly reporting pack, a client letter, tidying a messy spreadsheet. Run them through Copilot this week, and if you have both model families enabled, run them through both. The differences are bigger than people expect, and which model wins depends on the task rather than the branding.

Then answer one governance question: can anyone in your firm say whether Anthropic models are switched on in your tenant? Whichever way the setting points, it should be a decision someone made deliberately, not a default nobody noticed.

One practical note to finish. The rollout is gradual and availability can vary by tenant and by app, so do not read anything into GPT-5.6 not appearing in your selector yet.

A better model only pays off if people use it well on real work. Our Microsoft 365 Copilot training is built around exactly that, and if you want a straight answer on where your model and data setup stands, book a free consultation.

Sources checked

Last checked: 30 July 2026.

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Common questions

Questions about GPT-5.6 in Copilot

Do I need to do anything to get GPT-5.6 in Copilot?
For most tenants, no. Microsoft is rolling it out across Word, Excel, PowerPoint, Copilot Chat and Copilot Cowork automatically, though timing varies by tenant and by app. If it is not in your model selector yet, it is on its way.
Is GPT-5.6 better than Claude in Copilot?
It depends on the task. GPT-5.6 is Microsoft's preferred model, tuned for Copilot and strong on fast, well-defined work. Many teams still get better results from Claude models on long documents and careful multi-step reasoning. If both are enabled, test them on your own real tasks.
Does GPT-5.6 stay inside Microsoft's environment?
Yes. GPT-5.6 runs inside Microsoft's environment under the standard Copilot commitments, with no separate opt-in. That is the practical difference from Anthropic models, which are processed outside it and are off by default for UK tenants.
We decided against enabling Claude. Does GPT-5.6 close the gap?
Largely, yes. Firms that keep everything inside Microsoft now get a frontier model for heavy multi-step work in Copilot Chat and Cowork. Claude remains a genuinely different option worth a deliberate decision, but saying no to it no longer means settling for less capable AI.

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