The new rule will go into effect on January 12, 2016. Everyone still running Windows Vista and Windows Server 2008 SP2 will have to update to IE9, Windows Server 2012 (pre-R2) must upgrade to IE10 and everyone else to IE11.
Any businesses that have standardized on older versions of IE should take note and upgrade their systems over the next year and a half to avoid compatibility problems.
After January 12, 2016, only the most recent version of Internet Explorer available for a supported operating system will receive technical support and security updates. For example, customers using Internet Explorer 8, Internet Explorer 9, or Internet Explorer 10 on Windows 7 SP1 should migrate to Internet Explorer 11 to continue receiving security updates and technical support. For more details regarding support timelines on Windows and Windows Embedded, see the Microsoft Support Lifecycle site.Full details at MSDN.
As some commercial customers have standardized on earlier versions of Internet Explorer, Microsoft is introducing new features and resources to help customers upgrade and stay current on the latest browser. Customers should plan for upgrading to modern standards—to benefit from the additional performance, security, and productivity of modern Web apps—but in the short term, backward compatibility with legacy Web apps may be a cost-effective, if temporary, path. Enterprise Mode for Internet Explorer 11, released in April 2014, offers enhanced backward compatibility and enables you to run many legacy Web apps during your transition to modern Web standards.