Hi, thanks for taking the time reading this question,

I have a customer using DirSync and, in Office 365, we only have users using this service but they do not use anything in the on premise environment. Do I need to consider a new CAL for those Office 365 users? Beacuse I need to create the users in the On Prem AD to be provisioned to Office 365.

Thanks in advance.

Regards.

CALs for what exactly? If asking for Exchange/SharePoint/SfB - the O365 enterprise plans include the equivalent of CAL user rights. If asking for Windows CALs, no. More info here: http://blogs.technet.com/b/volume-licensing/archive/2013/10/10/licensing-how-to-using-office-365-user-licenses-to-meet-cal-requirements.aspx

In any case, licensing questions should be clarified directly with Microsoft.