Office 2016 EOL: Action Plan for After October 14, 2025

What Changes on October 14, 2025

On October 14, 2025, Microsoft will stop all support for Office 2016. This means:

• No more security patches – vulnerabilities discovered after that date will go unaddressed.
• No more bug fixes or feature updates.
• No vendor SLA – Microsoft will not respond to incidents involving Office 2016.

Active support ended back on October 13, 2020. For the last five years, the software has been in extended support, but that ends completely on October 14, 2025. Office 2016 is not an LTS release, so there is no extended servicing channel available.

Why Full Migration by October 14 Is Unrealistic

A complete migration from Office 2016 across your entire estate before that date is no longer practical for most organizations. The remaining three months are insufficient for thorough testing, user training, and rollout, especially if you have complex add-ins, macros, or compliance workflows. Instead of rushing a half-baked migration, use the time left to stabilize your risk posture and prepare for a managed, longer-term transition.

Week-by-Week Action Checklist

Use this plan to make the most of the eight to twelve weeks remaining before EOL. Adjust the timeline based on your start date.

Weeks 1–2: Full Inventory

• Identify every system running Office 2016 – use your CMDB, SCCM, or manual scans.
• Note which users rely on Office 2016 and for what purposes (e.g., critical macros, third‑party plug‑ins).
• Flag standalone installations vs. volume licensed deployments.

Weeks 3–4: Isolate and Harden

• Segment Office 2016 devices from the general network where possible. Use VLANs or firewall rules to limit lateral movement.
• Apply all remaining security patches from Microsoft before October 14.
• Disable unneeded features (e.g., DDE, ActiveX) to reduce attack surface.
• Enforce strict application allow-listing (AppLocker, WDAC) on those endpoints.

Weeks 5–6: Test Migration Paths

• Begin pilot migrations to Microsoft 365 Apps or Office 2021 Pro Plus on a small, low‑risk group.
• Document any compatibility issues with add‑ins or macros and work with vendors on updates.
• Establish a fallback plan – if migration fails, you need a support option.

Weeks 7–8: Document Exposure

• Create a formal risk register entry for Office 2016 post‑EOL, approved by your CISO or risk committee.
• Update your cybersecurity insurance application – most carriers now ask about EOL software.
• Prepare a memo for external auditors and compliance teams explaining your migration timeline and compensating controls.

Weeks 9–10: Line Up Post‑EOL Support

• Evaluate third‑party maintenance for Office 2016. Providers like 3rd Party Support can deliver patches and SLAs long after Microsoft stops.
• Review contracts and budgets; third‑party support is typically faster and less expensive than a forced forklift upgrade.

Weeks 11–12: Execute Hardening and Communication

• Apply final system lockdowns: disable OLE/COM objects not in use, enforce macro signing, restrict file types.
• Train users on phishing risks, especially since unpatched Office vulnerabilities are a favorite entry point for attackers.
• Notify your business stakeholders that Office 2016 is now unsupported and that managed migration will continue under a support contract.

Covering Your Compliance and Audit Obligations

After October 14, running Office 2016 is not illegal, but it creates liability. Many regulatory frameworks (PCI‑DSS, HIPAA, SOC 2) require that you run supported software or document compensating controls. Your documentation from the action plan above will be your evidence. Share it with your auditor and insurance broker proactively.

Keeping Office 2016 Safe After EOL

Even with hardening, you cannot patch zero‑days after October 14. That’s where third‑party support fills the gap. Providers such as 3rd Party Support offer:

• Security patches and hotfixes for Office 2016.
• A service‑level agreement with guaranteed response times.
• Expert guidance on maintaining legacy installations in a secure, compliant way.

You don’t have to migrate overnight. You just need a plan and a partner who can keep the lights on while you move at your own pace.

Act Now – Time Is Short

The October 14, 2025 deadline is less than a quarter away. Use the checklist above to take control of your Office 2016 estate today. Inventory, harden, document, and secure a support contract before the patches stop. Contact us to discuss how third‑party support can bridge the gap for your organization.