Microsoft released Windows 8.1 Update 1 in April, but if you have yet to install it you won't be able to get the patches that are scheduled for release today and in the future for the OS.
Microsoft was going to cut off future patches to Windows 8.1 immediately after Update 1 was released, but after receiving feedback from users, the company decided to delay that move and allowed users who had not installed Update 1 to download the patches released in May. However, that grace period is officially over.
According to a Microsoft spokesperson:
Customers who rely on Windows Updates (as opposed to Windows Server Update Service commonly used in corporate environments), and who have chosen to manually select and/or download updates instead of accepting Windows' default update settings to automatically install, and who have then deselected the Windows 8.1 update for download or installation, will not see subsequent updates because they only apply once the Windows 8.1 Update is installed. Manually downloading these subsequent updates will result in failed installation for the same reason.
Windows 8.1 Update 1 offers users a number of improvements, especially for old fashioned mouse and keyboard desktop operators who want to navigate the Modern UI. Microsoft is rumored to have a second large feature update for Windows 8.1 in the works for a launch later this fall but so far the company has not confirmed those reports.