No mainstream support end date. Extended support ended on January 12, 2016; 5 years and 11 months ago: Windows 8.1: October 17, 2013; 8 years ago () Windows 8.1 Pro, Windows 8.1 OEM, Windows 8.1 Enterprise NT 6.3 Mainstream support ended on January 9, 2018. Extended support will end on January 10, 2023. Windows Server 2012 R2