Microsoft has given notice to its original equipment manufacturer (OEM) partners that they must no longer sell personal computers with operating systems older than Windows 10 from the middle of next year.
Windows 8 PC sales must end July 1 next year Australian time.
Windows 7 Professional and Windows 8.1 can no longer be preinstalled on new computers from November 1, 2016, Microsoft said in its updated Windows Lifecycle Fact Sheet.
The Home Basic, Home Premium and Ultimate editions of Windows 7 were sunset on November 1 last year by Microsoft.
Windows 7 launced in October 2009. Microsoft has permitted it to live on substantially longer than Windows 8, which saw first light in 2013, and Windows 8.1, which arrived in 2013.
Enterprise customers using Microsoft's volume licensing scheme can continue to access prior versions of Windows, with some caveats.
"Licenses will continue to be available through downgrade rights after the end of general availability," Microsoft said.
"General availability of licenses for the previous version of Windows will cease as soon as the new version is available, or when otherwise determined by Microsoft. However, we will make media available for the current version as well as the previous two versions."
All editions of Windows 7 are already out of mainstream support. Microsoft will continue to provide extended support for Windows 7 until January 14, 2020 for a fee.
Windows 8 and 8.1 will go out of mainstream support on January 9, 2018, and extended support by January 10, 2023.
Microsoft's Windows 10 operating system will cease to receive mainstream support by October 2020, and extended support by October 14, 2025.