Microsoft support deadline: check Office 2021 and Windows 11 24H2 before 13 October

Two Microsoft deadlines fall on the same day

Microsoft has confirmed that support for Office 2021 ends on 13 October 2026. This includes the Office 2021 applications commonly installed through a one-off licence. Commercial Office LTSC 2021 installations reach the end of support on the same date.

After the deadline, Microsoft will no longer provide normal security fixes, bug fixes or technical support for these Office releases. Word, Excel and Outlook may continue to open, but newly discovered vulnerabilities will not be corrected.

Windows 11 version 24H2 also reaches the end of servicing on 13 October 2026 for Home, Pro, Pro Education, Pro for Workstations and SE editions. Windows 11 Enterprise and Education follow a different lifecycle, so centrally managed school and business devices should be checked by edition as well as version.

Check which version of Office you have

Open Word or Excel, select File and then Account. Look under Product Information for the product name. If it includes Office 2021 or LTSC 2021, it needs an upgrade plan.

Microsoft 365 Apps is the subscription version of Office and is not affected by this particular Office 2021 deadline, provided it remains licensed, supported and able to receive updates.

• Microsoft Office Home and Business 2021
• Microsoft Office Professional 2021
• Microsoft Office LTSC Professional Plus 2021
• Microsoft 365 Apps for business
• Microsoft 365 Apps for enterprise

Check the Windows edition and version

Right-click Start, select Settings, open System and then About. Under Windows specifications, record both the edition and version. Alternatively, type winver into the Windows search box and open the result.

A computer showing Windows 11 Pro, version 24H2 is affected by the October deadline. The same applies to Home, Pro Education, Pro for Workstations and SE editions running 24H2.

For an organisation with several computers, create a central list containing the computer name, user, location, Windows edition, Windows version and Office product. This avoids relying on users to notice update warnings themselves.

Choose the right upgrade route

For Windows 11 24H2 Home and Pro devices, the normal route is an upgrade to a currently supported Windows 11 release approved for that computer. Unmanaged devices may receive a newer release through Windows Update, while managed business and school devices may require their update policies to be changed.

For Office 2021, Microsoft recommends moving to Microsoft 365 Apps. Organisations that require a non-subscription installation can consider Office LTSC 2024, subject to licensing, compatibility and future support requirements.

Do not assume that replacing Office also upgrades Windows, or vice versa. They must be checked and updated separately.

Test before deploying widely

Feature and application upgrades can affect specialist software, document templates, macros, Outlook add-ins, printers, scanners and older hardware drivers. Test a representative group before changing every computer.

• Confirm that important files and settings are backed up.
• Test finance, manufacturing, education and other specialist applications.
• Check Outlook profiles, shared mailboxes and Office add-ins.
• Confirm that printers, scanners and other essential equipment still work.
• Record any recovery keys needed for encrypted devices.
• Schedule restarts outside important working or teaching periods.
• Complete the wider rollout promptly once testing succeeds.

Practical deadline checklist

The aim is not to rush into unnecessary purchases. A clear inventory will show which computers only require software updates, which need licensing changes and whether any genuinely require replacement.

• Identify every business and school computer.
• Record the Windows edition, Windows version and installed Office product.
• Flag Office 2021, Office LTSC 2021 and Windows 11 24H2 installations affected by the deadline.
• Check that backups are current and recoverable.
• Confirm compatibility with important software, add-ins and equipment.
• Test upgrades on a small group of computers.
• Plan the main rollout and required restarts.
• Recheck the inventory after deployment and investigate any computer that has not upgraded successfully.