Sow Source Selection: Fixed Budget Method for Procurement

PMBOK v8 Definition

The fixed-budget method is a source selection analysis technique where the buyer discloses the available budget to invited sellers in the request and selects the highest ranking technical proposal within that budget. This method is appropriate only when the statement of work (SOW) is precisely defined, no changes are anticipated, and the budget is fixed and cannot be exceeded. The buyer must ensure that the budget is compatible with the SOW and that the seller will be able to perform the tasks within the budget.

Why It Matters for the Exam

This concept appears frequently in PMI exam questions related to Procurement Management and Source Selection Analysis. Expect situational questions where you must identify which selection method applies based on project constraints—particularly when the budget is fixed and scope is precisely defined. Questions often test your ability to distinguish the fixed-budget method from other selection methods like least cost or sole source.

Key Points to Remember (for the exam)

• Definition: Disclose budget to sellers → select highest ranking technical proposal within budget
• Prerequisites: SOW precisely defined, no changes anticipated, budget fixed and cannot be exceeded
• Buyer Responsibility: Ensure budget is compatible with SOW and seller can perform within budget
• Seller Behavior: Sellers adapt scope and quality of their offer to the budget constraint
• Key Contrast: Unlike least-cost method, fixed-budget prioritizes technical ranking over lowest price
• Common Confusion: Fixed-budget is NOT sole source—sole source is used when only one verified source exists (patents/exclusive rights)
• Transparency Requirement: Include evaluation method in tender documents so bidders know how they will be evaluated

Typical PMI Exam Example

A project manager is procuring a specialized software development service with a strict, non-negotiable budget of $500,000. The SOW is detailed and unlikely to change. The buyer discloses the budget to three invited sellers. Which source selection method is being used? Answer: Fixed-budget method—the buyer selects the highest ranking technical proposal within the disclosed budget.

PMI Exam Traps

• Trap: Confusing fixed-budget with least-cost method Reality: Fixed-budget selects highest technical proposal within budget; least-cost selects lowest cost proposal meeting requirements

• Trap: Assuming fixed-budget means choosing the lowest bidder Reality: The method selects the highest ranking technical proposal, not the cheapest, as long as it stays within budget

• Trap: Thinking fixed-budget is appropriate when scope may change Reality: This method requires SOW precisely defined with no anticipated changes

• Trap: Confusing fixed-budget with sole source selection Reality: Sole source is used when only one verified source exists (patents/exclusive rights); fixed-budget involves multiple invited sellers

Important PMI Connections

Quick Review Questions

1. What are the three conditions that must be met for the fixed-budget method to be appropriate?

2. When using the fixed-budget method, what must the buyer ensure regarding the budget and the statement of work?

3. How do sellers typically respond when they receive a disclosed budget in the fixed-budget method?

4. What is the key difference between fixed-budget and sole source selection methods?

5. Why is it considered good practice to include the evaluation method in tender documents?

PMBOK v8 Reference

Section X4.6 – Source Selection Analysis (Fixed-budget method) Section X4.7 – Source Selection Criteria Appendix X4 – Procurement Process Overview