You may recall that Microsoft had previously made the recently released Update 1 for.1 a requirement for receiving future security updates, and that the original deadline was this month's Patch Tuesday, which occurs tomorrow, on May 13. Because Update 1 has not rolled out as quickly as expected, however, Microsoft has now extended this deadline another 30 days, and this month's Patch Tuesday updates will be available to Windows 8.1 users who have not yet installed Update 1 too.
For more information about Windows 8.1 Update 1—or what Microsoft calls "the Windows 8.1 Update"—please read my exhaustive review. Long story short, Update 1 is a step down a road towards making Windows 8.x ever more acceptable to all of Microsoft's users, in this case especially those with traditional mouse- and keyboard-based PCs.
But in addition to all the functional changes in Update 1, there's a side-story that some have tried to paint as a bizarre conspiracy theory: With this update, Microsoft has reset the baseline for future security updates for Windows 8.1. That is, if you want to get these future security updates, you will need to get Update 1 first.
This isn't controversial or unprecedented, though many are painting it as such. To be honest, I find the whole "debate" around this to be pointless. It is what it is.
But ... Some users have had trouble updating to Update 1 for whatever reasons. Some more stubborn types have simply decided not to update. So today, Microsoft announced that it is extending its Update 1 requirement for security updates out another 30 days. So you basically have until June's Patch Tuesday—instead of May's—to get Update 1 installed.
"While we believe the majority of people have received the update, we recognize that not all have," a Microsoft statement notes. "We've extended the requirement for our consumer customers to update their devices to the Windows 8.1 Update in order to receive security updates another 30 days to June 10th."
It's simple: If you don't upgrade to Update 1 by this new deadline, you will no longer receive security updates. Update 1 is the baseline for Windows 8.1 support going forward.