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Licensing a VDI Environment

Can anyone share information on how to license Microsoft in a VDI environment - both from a thin client and a windows device?  I have heard multiple opinions on this, so trying to determine which is right.  My understanding is that if the customer does not have software assurance on their desktop OS, that a VDA license is required, regardless what VDI is in place (RDS, Citrix, Horizon View, etc) and regardless if it is a zero/thin client or a windows Pro device.  


Also, I have also received different information on what the VDA license includes.  Some say that a Windows CAL is included with VDA and others have said that the RDS and Windows CAL is included (one of my scenario's include licensing for Citrix access, so the RDS CAL is needed.


Any help with this would be greatly appreciated!


@Jennie . You can find a licensing brief that explains licensing scenarios like this here: Licensing Documents (microsoft.com)

This brief is a general explanation, but not the official licensing terms (licensing briefs may become outdated when terms change) -  the official licensing terms (where opinion becomes fact ) can be found here: Microsoft Product Terms


Some direct answers to your question - note that my response is just to increase general understanding of applicable terms, this is not an official licensing statement.


First, it is important to understand that there might differences between licensing programs - one fundamental difference is that when Windows clients is licensed via MCA (For example, from a CSP Partner) there is only allowance for virtual desktop in Azure or with an outsourcing partner - while if licenses are obtained in EA, Open Value etc. with Software Assurance customer can run virtual desktop on their own server on their premises. Thios applies to both Windows 11 E3 licenses and VDA licenses.

This can be seen when comparing licensing terms for Windows Client in MCA and in other programs.


  • MCA terms only contain a section about "Windows 11 Virtualization" that describes virtual desktop rights in Azure/outsourcing partner and Azure Virtual Desktop: Microsoft Product Terms
  • EA terms (as example) contain an additional section in Software Assurance Benefits reg. "Remote Virtualization": Microsoft Product Terms which effectively allows virtual desktops on customers premises as well.

Reg. VDA license vs. normal Windows 11 E3/Enterprise licenses:

The difference is what device is used to access the virtual desktop.

  • A Windows 11 Enterprise per-device license can only be assigned to a device, if the device has a qualifying OS license (e.g. Windows 7/8/10/11 Pro, IoT Enterprise) .
  • A Windows 11 E3 per-user license can only be assigned to a user if the user has a primary work device with a qualifying OS license. If the device to access the virtual desktop (or users primary work device) does not have an eligible Windows license, the VDA license is required. Alternatively, since the October 2022 product terms update, Microsoft 365 F3/E3/E5 may also be assigned to a user with any type of work device to access virtual desktops. 

This ruling can be found in the Windows client product terms, and is the same for all licensing programs - Microsoft Product Terms - see "License Assignment for Windows Desktop Operating System Licenses" section.


To your assumption reg. that the requirement of usiong VDA vs. Windows license depends on having SA on the device - it does not matter if the device accessing the virtual desktops has Software Assurance or not - confirmed indirectly by the lack of such a requirement in the product terms.


Reg. Thin Client - note that "Windows Enterprise IoT" is a qualifying OS license", some thin clients might come with this license and then customer can go for the cheaper Windows 11 E3/Enterprise license. If thin client is based on another license type like Linux, the more expensive VDA license is required. This is because a customer runing devices with a qualified OS license already has made some investment in Windows (OEM) licenses.


Reg. VDA & included CALs - there are no CALs included. Microsoft 365 E3/E5 does include a Windows CAL (CAL-equivalent access rights), but not a RDS CAL.

Proof for this can be found when looking in the Windows Server product terms since this outlins what CALs are eligible for accessing the server: 

Microsoft Product Terms


For normal Windows CALs the types of CALs are listed - it also includes sonme reference to CAL-equivalent licenses mentioned here: https://www.microsoft.com/licensing/terms/product/CALandMLEquivalencyLicenses/ where you can see what M365 plans include CALs. For RDS CALS the same section in the WIndows Server product terms does only mention Windows RDS CALs, not other licenses.

RDS CALs are required whenever you access a Server with RDS roles installed, or " to host a graphical user interface (using the Windows Server 2022 Remote Desktop Services functionality or other technology)."

In case of Citrix, or any other VDI platform, it really depends if Windows RDS roles are used in the deployment - if no RDS roles are used and there is no Windows Server-based session host (which I assume, since the scenario you asked for is VDI using Windows Desktops), then no RDS CAL would be required.


This also answer the question if there are differences reg. which platform is used to depoloy virtual desktops - Hyper-V, VMware, Citrix:

  • There is no difference reg. if VDA or normal Windows license is required - this only depends on the device used to accessing the device.
  • Reg. need for RDS CAls, there is a difference - when using Hyper-V you typically deploy VDI as part of a Remote Desktop Virtualization Host deployment, so using Windows RDS services, thus RDS CALs are required for that.


Kind regards, Janosch (Note: Leaving role as of March 2023, don't expect further answers. Connect with me via LinkedIn: https://linkedin.com/in/janoschulmer)