How do I setup a work breakdown structure and filter work items in a hierarchy?

Question

How do I setup a work breakdown structure and filter work items in a hierarchy?

Answer

Work Breakdown Structure Definition

The work breakdown structure (WBS) is used to organize work into a series of components, such as projects, phases, tasks, etc. You can define up to 5 components, and name each level as you need.

Here are some typical use cases:

Use Case #1: Client Project Time and Expense Tracking 
Client > Project > Phase > Task 

Use Case #2: Construction Time, Expense, Production and Asset Tracking

Job > Cost Code, or Job > Phase Code > Cost Code

WBS components have the following properties:

Enabled:
Indicates whether the WBS component is enabled.

Dependent:
If checked then the WBS component may depend on another WBS component. For example, if you have a two-level WBS (e.g. Projects and Tasks) checking the dependent check box for the Task would indicate that the list of tasks presented to an employee might depend on which project was selected.

WBS Component:

This is the component's built-in system name. This name can be modified using the name and plural fields.

Name:
A custom singular name of a component: "Customer", "Job", "Phase Code," "Cost Code".

Plural:
The plural name of the component: "Customers", "Jobs", "Phase Codes," "Cost Codes".

Dependent:
In the Dependent column you can set dependencies between WBS components to have a parent/child relationship. Dependencies allow you to limit or scope a child item to a parent item. For instance, you might want to limit some Phase Codes to specific Jobs. To do this,  

1. Navigate to to System>Work Breakdown Structure>Edit.
2. Enable and edit the terminology for each WBS item level you need.
3. Then check the appropriate "Dependent" check box. Check the child item below the parent where you want create a dependency.  For example, Cost Code can be set to "Yes - Parent Required." This setting requires that a child WBS item must be assigned to a parent for users to be able to search for and add the child WBS item. 
4. You can have 'global' WBS items that are always available, whether a parent selection is made or not. This WBS component must be enable as "Yes - Parent Optional." This setting will restrict those children that are assigned to only the parents they are assigned. Those that are not assigned will be available to all parents.
5. To limit a cost code to one or more specific jobs, navigate to the cost code profile, go to the Jobs section and click the show/hide button. Then click the Add button to add the appropriate jobs.
6. Then, when employees select a job and then browse for cost codes, they will only see the assigned cost codes.
7. Note that dependencies take effect on time and expense sheets, as well as for reports that allow you to filter based on customers, projects, etc., such as the "Timesheet Details" or "Expense Details" reports.

You can modify dependency settings on WBS components manually. You can also do so using the WBS components import tool. 

See: How do I import work items (clients, projects, phases, tasks)? – Help Center (zendesk.com)