Enterprise customers can now select to buy an extra six years of support for Windows Server and SQL Server.
The new Premium Assurance extension offers a total of 16 years support, up from a current maximum of 10.
It is aimed at customers whose mission-critical and legacy applications aren't ready to move to the cloud, and which need to continue to run without disruption.
Windows Server and SQL Server currently receive new features, security, and non-security updates from Microsoft during the initial five-year Mainstream Support period. Non-security updates are available for a further five years with the Extended Support option.
Customers with the six-year Premium Assurance add-on will only receive security updates and bulletins rated "critical" and "important", Microsoft said.
Premium Assurance pricing will intially be five percent of the license cost, but this offer is valid only for purchases made from March to June 2017.
After that, Microsoft will introduce a tiered pricing model that increases the Premium Assurance charge every year.
It starts at 7 percent of license purchases between July 2017 and June 2018, going to 9 percent between July 2018 and June 2019, and 12 percent from July 2019 onwards.
Windows Server products that can be covered by Premium Assurance include 2008, 2008 R2 Standard, Datacentre and Enterprise Editions, as well as 2012 and 2012 R2 Standard and Datacentre. The recently released Windows Server 2016 (Standard and Datacentre) editions are also eligible.
SQL Server 2012, 2014 and 2016 Standard and Enterprise editions are eligibile for Premium Assurance, Microsoft said.
To be eligible for Premium Assurance, customers must buy Windows Server or SQL Server before the version purchased goes out of support, and as add-ons to Software Assurance.
Customers must also buy Premium Assurance for all servers with active Software Assurance that were bought under Microsoft's Enterprise Agreement, Enterprise Agreement Subscription, Enrollment for Education Solutions and its Server and Cloud Enrollment.
Server licences bought via programs outside the above agreements and enrollments are not eligible for Premium Assurance, Microsoft said.
Premium Assurance will be available worldwide early next year.