Microsoft quietly flipped a switch on July 9, 2024, making GPT-5.6 the new default AI model across Word, Excel, PowerPoint, Copilot Chat, and Cowork in Microsoft 365 Copilot. The change, which targets complex, multi-step work, marks the most significant under-the-hood upgrade since the assistant’s launch.

What Actually Changed

Starting July 9, the core reasoning engine behind Copilot’s most-used productivity features shifted from its previous model (widely believed to be GPT-4) to GPT-5.6. The rollout appears to be server-side, meaning users don’t need to install anything—they’ll simply begin noticing differences as the new model takes over requests.

According to the advisory Microsoft began circulating to customers, the model is tuned specifically for “complex, multi-step work.” While the company hasn’t published a detailed benchmark comparison, the phrasing suggests that Copilot should now handle requests that involve multiple actions chained together—like “take the data from this Excel sheet, create a PowerPoint slide summarizing the trends, and draft an email to my team with the highlights.”

The upgrade covers:
- Word – drafting, rewriting, and document analysis
- Excel – formula generation, data analysis, and visualization
- PowerPoint – slide creation, design suggestions, and narrative building
- Copilot Chat – general-purpose Q&A within the Microsoft 365 interface
- Cowork – the collaborative Copilot experience that works across files and meetings

Microsoft hasn’t said whether the rollout is gradual or instant for all tenants. Typically, enterprise-focused updates like this trickle out over several weeks, so some users may still be on the older model for a short time.

What It Means for You

For Everyday Users

If you’ve been using Copilot for things like writing meeting summaries or generating simple formulas, you might not notice an immediate, seismic shift. But the first time you give it a truly chain-of-thought task—say, “Read this contract, find the termination clauses, and draft a two-paragraph summary in plain English”—you’ll likely see fewer dropped steps and less need for follow-up corrections.

Early anecdotal reports (and Microsoft’s own messaging) suggest that GPT-5.6 maintains context better over longer conversations. That means less repeating yourself when building a document incrementally.

For Power Users and Analysts

If you regularly push Copilot with multi-part Excel formulas, conditional logic, or intricate PowerPoint narratives, this update could be a quiet productivity multiplier. The model’s focus on multi-step reasoning should translate to more accurate complex formula generation on the first try and better slide narratives that actually follow your outline.

For developers who use Copilot in Power Platform or custom integrations, Cowork improvements might mean more natural collaboration between Copilot and your workflows.

For IT Administrators

This is a cloud-side change, so there’s no update to deploy, no policy to enable, and no security patch to test (at least, not yet). However, admins should watch the Microsoft 365 Message Center for any notes about data handling or usage limits. While Copilot still operates within tenant security boundaries, model upgrades sometimes come with subtle changes in how prompts are processed or stored. No immediate action is required, but staying informed is good practice.

If your organization has opted for specific Copilot model versions via advanced settings, you may want to check that the shift to GPT-5.6 doesn’t override those preferences—though, so far, Microsoft hasn’t indicated any such conflict.

How We Got Here

Microsoft 365 Copilot launched in late 2023 built on OpenAI’s GPT-4, with the ability to orchestrate between the large language model, Microsoft Graph data, and Office apps. That first version was impressive but occasionally stumbled on tasks that required it to remember what it had done two steps earlier or to reason across non-linear request chains.

Behind the scenes, Microsoft has been iterating rapidly. The Copilot you use today is already a cocktail of models: GPT-4 for most tasks, a smaller tuned model for quick classification jobs, and specialized image generation via DALL·E. The jump to GPT-5.6 suggests that Microsoft is now leaning toward a model optimized for agent-like behavior—where the AI navigates multiple tools and data sources to complete a task rather than just responding to a single prompt.

Why the “5.6” label? OpenAI’s public model names don’t include a GPT-5.6, which has led to speculation that this is either a Microsoft-customized fork, a version number internal to the Copilot service, or perhaps a model from a different provider optimized specifically for the 365 context. What’s clear is that Microsoft can now tailor models to specific tasks, much like it already tailors Copilot experiences to individual apps.

The shift also aligns with a broader industry push toward “compound AI”—systems that plan, execute, and verify multi-step processes. Just a week before this rollout, Microsoft announced Copilot for Finance, a role-specific assistant that strings together multiple data sources in Excel and Outlook. GPT-5.6 seems purpose-built for that kind of heavy lifting.

What to Do Now

If you’re an end user: Start kicking the tires on more ambitious requests. Copilot’s interface doesn’t change, but the model does. Try prompts that combine creation and analysis: “Analyze this spreadsheet and create a document that explains the top three trends using charts from Excel.” Note where it used to stumble and see if it’s gotten smoother.

If you’re an IT admin: Monitor adoption and feedback. If your organization has been holding off on Copilot because the first-gen model wasn’t reliable enough for complex workflows, GPT-5.6 might be the catalyst to retest. Consider running a pilot with a subset of users who run multi-step tasks regularly—financial analysts, project managers, proposal writers—and gather qualitative feedback.

If you’re a developer building on Microsoft 365: Check the Graph API and Copilot extensibility docs for any model-specific behaviors. While the core interface shouldn’t break, subtle response formatting or latency changes are possible.

No special settings are required to get GPT-5.6. It’s the default now, and you can’t switch back. If you’re still seeing inconsistent behavior, wait a week or two for the rollout to complete fully.

Outlook

This is likely the first of several model upgrades we’ll see in the second half of 2024. Microsoft has invested billions in its AI infrastructure, and Copilot is the flagship consumer of that capacity. Expect more rapid model turnover as the company shifts toward smaller, faster, and more specialized models for different workloads.

Short-term, the next step might be a formal announcement with before-and-after benchmarks, something Microsoft has done in the past following quieter rollouts. Watch for updates at the Ignite conference in November.

Longer-term, GPT-5.6 could become the backbone of even more autonomous features—think Copilot handling entire weekly report generation cycles without being asked every step of the way. For now, though, the message is simple: your AI assistant just got a better brain. Go see what it can do.