Microsoft has updated its servicing model. The Semi-Annual Channel (SAC) offers twice-per-year feature updates that release around March and September, with an 18-month servicing period for each release. Starting with Windows 10, version 1809, feature updates for Windows 10 Enterprise and Education editions with a targeted release month of September will be serviced for 30 months from their release date (more information can be found here).
If you are not using Windows Update for Business today, “Semi-Annual Channel (Targeted)” (SAC-T) has no impact on your devices (more information can be found here) and we recommend beginning deployment of each Semi-Annual Channel release right away to devices selected for early adoption and ramp up to full deployment at your discretion. This will enable you to gain access to new features, experiences, and integrated security as soon as possible.
If you are using Windows Update for Business today, refer to the table below to understand when your device will be updated, based on which deferral period you have configured, SAC -T or SAC.
Notice: October 8, 2018: We have paused the rollout of the Windows 10 October 2018 Update (version 1809) for all users as we investigate isolated reports of users missing some files after updating. We apologize for any inconvenience this may have caused. We will provide an update when we resume updating customers. For reference, please see Windows 10 update history for additional information.