Work Package: The Lowest Level of the WBS for Cost and Duration Estimation

PMBOK v8 Definition

A work package is the work defined at the lowest level of the work breakdown structure (WBS) for which cost and duration can be estimated and managed. The level of decomposition is often guided by the degree of control needed to effectively manage the project. The level of detail for work packages varies depending on the size and complexity of the project.

Why It Matters for the Exam

The work package concept appears frequently in questions about Scope Management and WBS decomposition. PMI tests your ability to distinguish the work package from other WBS components, especially planning packages and control accounts. Expect questions asking you to identify the correct level for estimation, the relationship to control accounts, and the decomposition activities.

Key Points to Remember (for the exam)

• Lowest WBS Level: The work package is the lowest level of the WBS, with a unique identifier that provides structure for hierarchical summation of costs, schedule, and resource information.
• Estimation Basis: Cost and duration can be estimated and managed at the work package level.
• Control Account Relationship: Each work package is part of a control account. A control account has two or more work packages, though each work package is associated with a single control account.
• Decomposition Activities: Decomposing total project work into work packages involves: identifying deliverables and related work, structuring and organizing the WBS, decomposing upper levels into lower-level components, developing and assigning identification codes, and verifying appropriate decomposition.
• Code of Accounts: Work package identifiers form a code of accounts for hierarchical summation.
• Planning Package Distinction: A control account may include one or more planning packages (which are different from work packages).
• Performance Measurement: A control account is a management control point where scope, budget, and schedule are integrated and compared to earned value for performance measurement.

Typical PMI Exam Example

A project manager is decomposing the project work. The WBS shows a component at level 3 for which the project team can estimate cost and duration. The project sponsor asks: "What is this component called?" The correct answer is: work package—because it is the lowest WBS level where cost and duration can be estimated and managed.

PMI Exam Traps

• Trap: Confusing work package with planning package

  • Reality: A work package is the lowest detailed level; a planning package is a temporary placeholder for work not yet decomposed within a control account.

• Trap: Thinking a control account equals a work package

  • Reality: A control account has two or more work packages. Each work package is associated with a single control account.

• Trap: Assuming all WBS levels have the same level of detail

  • Reality: The level of decomposition varies depending on the size and complexity of the project and the degree of control needed.

• Trap: Believing work packages are only for cost estimation

  • Reality: Work packages allow estimation and management of both cost and duration.

Important PMI Connections

Quick Review Questions

1. What is the lowest level of the WBS for which cost and duration can be estimated and managed?

2. How many work packages can a control account contain?

3. What are the five activities involved in decomposing total project work into work packages?

4. What is the difference between a work package and a planning package?

5. What do work package identifiers form in the WBS structure?

PMBOK v8 Reference

Section 5 – Tools and Techniques (WBS Decomposition and Work Package Definition)