In Microsoft 365 projects, one question keeps coming up lately. What actually happens to Microsoft 365 Apps on Windows 10 after October 14, 2025? Microsoft has announced that Microsoft 365 Apps will keep receiving security updates on Windows 10 until October 10, 2028. At first that sounds like good news, but I think it gives people a false sense of safety. Many organizations still running Windows 10 are unclear about what this means for support, security and day-to-day operations. Keeping Windows 10 alive involves a lot more than buying time or an ESU license.

Microsoft 365 Apps on Windows 10 get security updates but no future-proofing

The facts first. Office 2016 and Office 2019 both reach end of support on October 14, 2025 (details from Microsoft). Microsoft 365 Apps (formerly Office 365 ProPlus) will keep getting monthly security updates on Windows 10, but the operating system underneath is out of support unless you buy Extended Security Updates (ESU) (my background post on Windows 10 ESU). After that date, feature updates and new functions for the apps are not guaranteed on Windows 10. In practice you get the minimum: security fixes and nothing new. Each feature Microsoft ships for Microsoft 365 Apps widens the gap between Windows 10 and Windows 11.

The support side deserves more attention than it usually gets. After October 2025, opening a Microsoft 365 Apps support case for a Windows 10 device is a gamble. Microsoft can point to the unsupported OS and decline to engage, and I expect it will, even if you paid for ESU. Bugs, performance problems or broken integrations will usually come back to you with a reference to end of support.

A slower update channel does not keep features on Windows 10

Some admins assume they can move to a slower update channel (for example Monthly Enterprise Channel instead of Current Channel) and stay out of trouble. That doesn't work. After October 2025, Windows 10 clients receive only security updates, whichever channel they are on (overview of update channels). Feature updates and improvements are now reserved for Windows 11. New Microsoft 365 integrations, Copilot enhancements and support for modern formats will simply skip Windows 10.

This hurts quickly in regulated environments and wherever add-ins or third-party integrations matter. ISVs stop certifying for Windows 10, newer authentication methods may fail, and compatibility problems with other Microsoft services start to add up. What I see in practice is a growing number of isolated workarounds and manual drift, which raises both the operational effort and the security risk.

Practical tip: If you have to keep running Microsoft 365 Apps on Windows 10, write the risk down explicitly. List the support limitations, the missing features and the absence of third-party guarantees. That record is worth a lot in an audit and can protect you when a problem escalates.

Support becomes best effort and the risk needs documentation

From October 2025 on, Microsoft 365 Apps on Windows 10 fall into a "best effort" support state. Compatibility and functionality fixes stop. Microsoft can close a ticket without looking into it closely, just because the OS isn't supported. Windows 10 ESU doesn't help you here either, since it covers only the operating system and not application-level support or features.

IT teams should therefore expect more self-help, more testing and more surprises from updates. Every new Microsoft 365 Apps feature after October 2025 will be built and tested for Windows 11 only. My guess is that Teams, Outlook, Copilot and SharePoint scenarios will show the problems first, and by 2026 Windows 10 devices will feel cut off from the rest of the environment.

Office 2016 and 2019 reach the end of the road

Some organizations think about keeping old Office clients around as a fallback. That isn't an option. Office 2016 and Office 2019 lose all support and security updates on October 14, 2025 (more on planning for this). From then on there are no patches, no fixes and no support from Microsoft, no matter which OS they run on. Using these versions after that date is a serious security and compliance problem.

Office LTSC 2021 or 2024 may look like a way out, but their support is time-limited as well, and they get no new features. If you need modern collaboration, Copilot integration or current security standards, they don't replace Microsoft 365 Apps on a supported platform.

Security updates are no reason to stay on Windows 10

Running Microsoft 365 Apps on Windows 10 after October 2025, with or without ESU, means accepting a risk that grows every month. The apps still get basic security updates, but they stop moving forward. Daily work gets slower, less productive and more prone to errors. Pointing out that security updates continue misses what matters, because new Microsoft 365 features, integrations and proper support are all aimed at Windows 11 now.

A migration can be messy. Still, the alternatives cost more, are less secure and carry more risk over time. From what I've seen, the only path that holds up is to plan the move to Windows 11 for every productive endpoint. If legacy applications force your hand, use ESU as a short bridge, and only with a clear exit plan.

flowchart TD
    a["Windows 10"] --> b["Microsoft 365 Apps"]
    a --> c["ESU (optional)"]
    b --> d["Security updates until 2028"]
    b -.-> e["No new features"]
    b -.-> f["Limited support"]
    g["Windows 11"] --> h["Microsoft 365 Apps"]
    h --> i["Full updates and support"]

Figure: Microsoft 365 Apps on Windows 10 get security updates, but have no future.

I don't treat security updates as a strategy

To me, security updates for Microsoft 365 Apps on Windows 10 until 2028 are no excuse to put off the migration. They give you a little extra time to finish the Windows 11 rollout, and that's all. If you wait, you'll pay for it with higher support costs, unhappy users and missed chances to modernize. Document your risks, plan the move and make good use of this window, because the gap between the old platform and the new one only gets harder to close.