How to grant access to resources to add Expense on Engagement?

Question
How can access be given to a resource to add expenses on engagement level, i.e. without specifying a project or a task name?

Answer
It is not possible to add expenses against an engagement. Expenses can be entered against a project or a task. This is controlled by settings in the project:

1. Expense only users. Here users can be added that are allowed to create expenses against the project without being assigned to a task
2. Allow Resources with task assignments to enter expenses

When this is selected, resources with a task assignment can create expenses against this project or a task.

It is not possible to create an expense with the project field empty. If this is what should be achieved, you might create an extra project 'Expenses' that will just be used to enter expenses for that engagement.