Claude vs. GPT in Microsoft 365 Copilot: The New Power of Choice

Microsoft 365 Copilot now supports Anthropic's Claude models alongside OpenAI's GPT, giving enterprise users the ability to choose between two of the world's most capable AI systems directly inside the productivity apps they already use. Here is what that means for your organization.

What Changed: Claude Comes to Microsoft 365

Microsoft 365 Copilot now supports Anthropic's Claude models alongside OpenAI's GPT, giving enterprise users the ability to choose between two of the world's most capable AI systems directly inside the productivity apps they already use. Announced on March 9, 2026, this shift marks the end of Microsoft's exclusive reliance on OpenAI and signals a broader multi-model AI strategy that will reshape how organizations approach AI-powered productivity.

This is a significant departure. Microsoft had previously maintained an exclusive relationship with OpenAI, investing $13.8 billion in the company and building its Copilot AI assistant entirely on GPT. The introduction of Claude is built on the foundation of a separate $30 billion Azure compute deal with Anthropic, announced in November 2025, under which Anthropic will run Claude on Azure infrastructure powered by Nvidia's latest GPU architecture.

Microsoft 365 Copilot now supports both GPT and Claude models. Users can select their preferred AI engine from a dropdown in the Copilot interface, with no separate apps or subscriptions needed. The strategic logic is clear: Microsoft positions Azure as the critical cloud platform for the AI era by hosting both leading model families.

Why Anthropic? The Rise of Claude in Enterprise AI

Anthropic, the AI safety and research company behind Claude, has been gaining significant traction in enterprise environments. Despite OpenAI's broader name recognition, many professionals and organizations have gravitated toward Claude for its reasoning depth, writing quality, and more measured analytical style.

Independent benchmarks support this shift. Claude Opus scores 91.3% on the GPQA Diamond benchmark for graduate-level scientific reasoning. On real-world software engineering tasks (SWE-bench Verified), Claude Opus achieves 80.8% compared to GPT's approximately 80%. Anthropic has also doubled its enterprise market share over the past year, growing from 12% to 24%.

"Announcing Copilot Cowork, a new way to complete tasks and get work done in M365. When you hand off a task to Cowork, it turns your request into a plan and executes it across your apps and files, grounded in your work data and operating within M365's security and governance boundaries."

Satya Nadella, CEO, Microsoft

Head-to-Head: Claude vs. GPT in Copilot

The two model families bring genuinely different strengths to the table. Rather than one being universally better, the choice comes down to what type of work you are doing.

Deep Reasoning: Why Claude Uses 23 Steps to GPT's 9

One of the most striking differences shows up in Excel tasks. When asked to build a complex, multi-functional workbook from scratch, Claude Opus performs 23 reasoning steps compared to GPT's 9. Those additional reasoning cycles translate into more sophisticated outputs: functional dropdown menus, conditional formatting rules, color-coded legends, and built-in data validation.

This deep reasoning capability is particularly valuable for financial modeling, data analysis workflows, and any scenario where a spreadsheet needs to function as a working tool rather than a static grid of numbers. Claude does not just fill in cells; it builds interactive, automated workbooks that save hours of manual setup.

For organizations that rely heavily on Excel for budgeting, project tracking, or operational dashboards, this distinction alone may justify experimenting with Claude for spreadsheet-intensive tasks.

Honest Critique vs. Positive Bias: How Does Each Model Review Documents?

Perhaps the most practically important difference for knowledge workers is how each model handles business proposal review. Claude consistently identifies weaknesses, flags missing elements, and highlights potential risks. GPT tends to offer more encouraging, affirming feedback that validates the existing approach.

Neither style is wrong in isolation, but they serve different purposes. If you are in the early brainstorming phase and want encouragement, GPT's supportive style can be valuable. If you are preparing to present a proposal to leadership and need to anticipate objections, Claude's critical lens is the better choice. Smart teams will use both: GPT for ideation, Claude for stress-testing.

What Is Copilot Cowork?

Copilot Cowork is an agentic AI tool, meaning it does work on your behalf rather than just providing answers like a traditional chatbot. Announced alongside the Claude integration, Cowork is a cloud-based AI agent powered by Anthropic's Claude that can execute multi-step tasks across the entire Microsoft 365 ecosystem.

"Cowork makes it easy to delegate work. Describe the outcome you want and Cowork automatically grounds the work in your emails, meetings, messages, files, and data. Powered by Work IQ, Cowork draws on signals across Outlook, Teams, Excel, and the rest of Microsoft 365 so it can act with the same understanding you bring to your job."

Charles Lamanna, President of Business Applications and Agents, Microsoft

Copilot Cowork is currently in Research Preview, with broader access through Microsoft's Frontier program expected in late March 2026.

How Does Copilot Cowork Handle Enterprise Security?

Copilot Cowork's security model is built on Microsoft's existing enterprise governance framework, meaning IT administrators retain full control over data, identity, and compliance. This is a significant change from standalone AI tools that historically operated outside the bounds of corporate IT controls. Because Cowork runs as a cloud-based solution within a customer's M365 Copilot tenant, all AI activity stays inside your existing security boundary.

"Cowork is built with enterprise needs in mind. Work is observable. Actions are transparent. Documents are immediately enterprise knowledge that's protected and ready to share. Progress can be reviewed, guided, or stopped. And everything operates within Microsoft's security, identity, and governance framework, so organizations can adopt these capabilities with confidence."

Jared Spataro, Chief Marketing Officer, AI at Work, Microsoft

For organizations that already use Microsoft's security tools like Defender and Entra, adopting Copilot Cowork is far more straightforward from a security perspective than trying to bring in a standalone AI vendor. All data stays within your existing M365 security boundary. If you need help configuring, managing, or applying these tools to AI, learn more about CloudFirst's Managed Microsoft Services.

The Anthropic-Pentagon Dispute: Context That Matters

Microsoft's move to integrate Anthropic comes with some political backdrop worth noting. In late February 2026, the Pentagon canceled a $200 million contract with Anthropic after the company refused to allow its AI to be used for mass surveillance or autonomous lethal weapons. The Trump administration subsequently directed federal agencies to cease using Anthropic's products and designated the firm a "supply chain risk."

However, a federal judge blocked the government's enforcement of that designation in late March 2026, ruling that the actions likely violated the law. Microsoft confirmed that Anthropic's products remain available to its customers throughout the dispute.

Anthropic's Claude remains fully available within Microsoft 365, and Microsoft has publicly committed to continuing the integration regardless of the government dispute. Enterprise customers face no disruption.

Pricing and Availability

Claude access is included in the standard Microsoft 365 Copilot license at $30 per user per month, with no additional cost. Users can switch between Claude and GPT models from a dropdown in the Copilot interface across Copilot Chat, Excel, Word, PowerPoint, the Research Agent, Copilot Studio, and GitHub Copilot.

Microsoft also introduced a new Microsoft 365 E7 enterprise bundle at $99 per user per month. The E7 tier includes Copilot, the Agent 365 agentic AI control suite for managing AI agents across the organization, and the Microsoft Entra Suite for comprehensive identity and security management. The E7 bundle launches May 1, 2026.

One important note for EU-based organizations: Anthropic models inside Microsoft products are currently excluded from the EU Data Boundary. All Claude processing happens in US-based data centers, and organizations in the EU, UK, and EFTA require admin opt-in to enable Anthropic models. Organizations with strict data residency or compliance requirements should evaluate this carefully before enabling Claude.

Should You Switch from GPT to Claude?

The smart approach is not to pick one AI model and ignore the other. Instead, match the model to the task. M365 Copilot now gives you the flexibility to choose, so here is a practical framework for deciding when to use Claude vs. GPT in your enterprise AI workflows:

The real power of this update is choice itself. Enterprise teams can now develop workflows that use the specific strengths of each model rather than being locked into a single AI paradigm.

What This Means for Your Organization

Microsoft's multi-model strategy is not just a product update; it reflects where enterprise AI is heading. The era of single-vendor AI lock-in is ending. Organizations that develop the internal expertise to evaluate, deploy, and govern multiple AI models will have a meaningful competitive advantage.

For IT leaders, the immediate action items are clear: evaluate your current M365 Copilot deployment, pilot Claude in departments that do heavy analytical or financial work, and ensure your security and governance controls are ready for multi-model AI operations. As a certified Microsoft partner, CloudFirst can help you navigate this transition and get the most from your enterprise AI investment.