What should organisations do first when Office 2016 or 2019 is nearing end of support?

Start with a usage and dependency audit. Identify every device still running Office 2016 or 2019, then map macros, add-ins, file workflows, and connected services that could break after support ends. That gives security, IT, and application owners a realistic migration scope and prevents last-minute outages, compatibility failures, and audit surprises when the October 14, 2025 cutoff arrives.

Why the first step has to be a dependency audit, not a migration checklist

The first move is to establish real usage, not assumed usage. Office estates usually fail at end of support because teams inventory versions but miss how those installs are actually used: macros, add-ins, shared templates, spreadsheets with embedded business logic, and links to external services. A dependency audit turns an abstract deadline into a concrete scope for remediation.

That scope matters because the risk is not just “old software,” it is broken workflows. If a workbook depends on a macro, an add-in, or a connected service that is not compatible with the target Office release, the migration can stall even when the new version is technically deployed.

What the audit should capture before support ends

Start by identifying every device still running Office 2016 or 2019, then classify what each installation actually does for the business. For many organisations, the important question is not which desktop has Office installed, but which user journeys, finance processes, reporting packs, document assemblies, and shared file locations depend on that installation to function correctly.

Devices and user groups still on the affected versions.
Macros, templates, and VBA-based workflows that are business critical.
Add-ins and integrations that alter document creation, mail handling, or reporting.
Connected services and file dependencies that may require a newer client or altered authentication flow.

This is the point where application owners, not just endpoint teams, need to be involved. A technical inventory alone will not show whether a broken add-in will block month-end close or whether a macro failure will create manual workaround risk for a regulated workflow.

Why dependency mapping prevents support-cutoff surprises

Dependency mapping is the control that converts end-of-support planning from reactive to manageable. It helps you separate simple version replacement from real remediation, such as rewriting macros, testing add-in compatibility, repackaging workflows, or sequencing upgrades around critical business cycles.

It also reduces hidden operational risk. Unsupported Office versions do not fail in one obvious moment; problems accumulate when users keep relying on untested documents, legacy automation, and integrations that were never validated for the successor platform. The organisations that get caught out are usually the ones that treated deployment as the finish line instead of the start of compatibility testing.

Risk and Threat Considerations

End-of-support dates create an exposure window where known weaknesses, broken dependencies, and unsupported configurations can persist in active use. The practical risk is that users continue to trust software that no longer receives security fixes while business processes still depend on it.

Failure mechanism: Unsupported Office installs can continue to execute macros, load add-ins, and interact with connected services even after compatibility or security gaps appear, which leaves organisations exposed to workflow failure, exploitability, and unplanned downtime.

Impact: The result can be interrupted business processes, delayed patching decisions, audit findings, and a wider attack surface if legacy documents or integrations remain in circulation after the cutoff.

Practitioner Guidance

What to prioritise: Treat high-value workflows first, especially anything tied to finance, legal, regulated reporting, or shared automation. A single failing add-in in a critical workflow is usually more urgent than a large number of lightly used desktop installs.

What to verify: Confirm which dependencies are truly business critical by testing the documents, templates, and add-ins themselves, not just checking software version numbers. If a workflow cannot be reproduced in the target environment, it is not ready.

Practitioner takeaway: The best first step is to discover operational dependency, because migration risk is driven more by what Office does for the business than by the version label alone.