Microsoft Office 2021: Support ends October 13, 2026

Microsoft is ending support for Office 2021 and LTSC 2021 on October 13, 2026 – a patch day that also marks the end of support for Windows 10 for end-users with the one-year extended support program. From that date, there will be no more security updates for Office LTSC 2021 and its associated apps.

Microsoft is reminding admins of this in the Microsoft 365 Message Center (MC1278920, copy at merill.net). This calls on not only end-users but also organizations and companies to migrate to Microsoft 365 Apps or Microsoft Office LTSC 2024.

Office 2021: No extended support

However, unlike for Windows 10, Microsoft is explicitly not providing an Extended Security Updates (ESU) program, where affected parties could purchase additional years of support with security updates. In a support document about the end of support, Microsoft explains that the Office 2021 apps will continue to function, but users will be exposed to serious and potentially harmful security risks.

Microsoft explains that after October 13th of this year, the company will no longer provide technical support, bug fixes, or security fixes for Office 2021 vulnerabilities that may still be reported or discovered. This includes security updates that can protect PCs from viruses, spyware, and other malware. Microsoft Update will no longer deliver Office 2021 updates, and Microsoft also excludes telephone or chat support. The online help will also not be maintained.

Just last October, support for Microsoft Office 2016 and 2019 ended. Smaller companies in particular are impacted by this. The versions were the dominant on-premises packages in mid-October 2025, with an installation rate of 65 percent. Those who have upgraded to Office 2021 there must now act again.

(dmk)