Can tasks and sub-tasks be assigned to unlicensed users

[Peter Walker]

I was wondering if I create a project that requires a task to be completed by someone outside of my team and doesn't has a JIRA Core or Service Desk license assigned to their account, would that work?

[Melissa Carter]

Clarification - assignees have to be created as JIRA users, but they don't actually have to have active seat licences to get email notifications, etc. Under Admin/User Management/Create User you can add names and email addresses without having to assign them to any group. 

[Nic Brough -Adaptavist-]

The assignee for a JIRA issue has to be a JIRA user.

JIRA Service Desk has a slightly different model, in that customers (who are mostly not JIRA users) can be the assignee, in a sort of "it's their problem because they raised it, and need to tell support that it has been fixed" way.

But someone who needs to work on an issue needs to be a user.