You have a SharePoint 2013 farm on a patch level before April 2017 CU and you plan to keep it running after April 10th, 2018? Start patching!
As communicated earlier, Mainstream support for SharePoint 2013 will end April 10th, 2018. After this date only security fixes will be provided for SharePoint 2013. Regular hotfixes can no longer be requested.
But this is not the only thing to consider after this date: starting with April 10th, 2018 the required patch level to request support for SharePoint 2013 will also change.
Currently all patch levels starting with SharePoint 2013 SP1 are supported. Starting with April 10th, 2018 this will change. In order to request support from Microsoft after April 10th, 2018 the SharePoint server farm has be on a patch level of April 2017 CU or later. A year later, after April 10th, 2019, the SharePoint server farm has be on a patch level of April 2018 CU or later.
This change is outlined in the Updated Product Servicing Policy for SharePoint 2013 published on TechNet.
Below is a table which outlines the required patch level for SharePoint 2013 till end of the extended support phase:
|SharePoint Server 2013 and SharePoint Foundation 2013 Releases||Support End Date|
|Service Pack 1||4/10/2018|
|April 2017 CU – March 2018 CU||4/10/2019|
|April 2018 CU – all future CU||4/11/2023|