Definition
A make or buy decision is an assessment of whether to perform an activity or produce an item internally or purchase it externally. The decision considers economics, capacity, capabilities, quality, and the reliability of the external supply option.
It is not simply a comparison between a supplier quote and the internal standard cost. The relevant question is what changes economically and operationally when the business chooses one option over the other.
Define the decision before comparing costs
Specify the required product or service, volume, quality, delivery performance, and decision horizon. A short-term overflow purchase and a permanent plant exit require different analyses.
Also define what capacity would actually be released and what the business could do with it. Empty floor space, available labor hours, and a saleable facility are different outcomes with different financial implications.
Do not assume all reported manufacturing cost disappears when production moves outside. Some overhead may remain, while new supplier-management, freight, quality, or transition costs emerge.
Separate costs that change from costs that move on paper
- Avoidable costs: Include future expenditure that would genuinely stop or decline under an option. Verify whether labor, support, utilities, or leases can change within the decision horizon.
- Incremental costs: Include new expenditure caused by the decision, such as external processing, inbound logistics, inspection, supplier oversight, or replacement capacity. Fixed costs can be relevant when the decision creates them.
- Unchanged allocations: Exclude reallocated costs from the difference between options when the total expenditure remains unchanged. Retain them in the enterprise forecast rather than presenting them as eliminated.
- Opportunity costs: Evaluate a credible alternative use of constrained resources. Count only the incremental contribution or proceeds supported by a feasible alternative, not an aspirational revenue estimate.
Past expenditure is not a reason to continue an unattractive operating choice. Future disposal proceeds, exit payments, new investment, and tax effects may still matter and should be assessed separately.
A hypothetical manufacturing comparison
Assume a business needs 50,000 identical components annually. Making them internally requires $900,000 of variable expenditure and $150,000 of fixed expenditure that can actually be avoided if production stops.
The internal cost report also allocates $250,000 of overhead that would remain after outsourcing. A qualified supplier quotes $21 per component, with another $2 per unit for inbound logistics and quality activities plus $50,000 annually for incremental supplier management.
| Annual cost element | Make | Buy |
|---|---|---|
| Internal variable expenditure | $900,000 | $0 |
| Avoidable internal fixed expenditure | $150,000 | $0 |
| Supplier component purchases | $0 | $1,050,000 |
| Inbound logistics and quality activities | $0 | $100,000 |
| Incremental supplier management | $0 | $50,000 |
| Relevant annual expenditure | $1,050,000 | $1,200,000 |
| Unchanged allocated overhead | $250,000 | $250,000 |
| Total scoped annual expenditure | $1,300,000 | $1,450,000 |
Comparing the $1.3 million internal report with the $1.05 million supplier quote would suggest a $250,000 reduction. The complete comparison instead shows buying costs $150,000 more annually before considering an alternative use of capacity.
Test the alternative use of released capacity
Now assume outsourcing would free a constrained resource that can support confirmed additional business producing $220,000 of annual contribution after all incremental operating costs. The same capacity cannot simultaneously support another benefit claim.
The $220,000 contribution exceeds the $150,000 additional buying cost, producing a modeled $70,000 annual operating advantage. That conclusion depends on actual demand, qualification, staffing, and the ability to realize the alternative production.
If transition requires $140,000 of one-time cash expenditure, a simplified first-year cash comparison is negative $70,000 even with a full year of the operating advantage. This illustration assumes operating benefits convert to cash within the year and excludes taxes, working-capital changes, and other investments.
That is not a complete investment appraisal or an EBITDA calculation. A long-term decision should model timing, remaining asset value, additional capital, risk, and discounted cash flows where appropriate.
Treat qualification and continuity as decision conditions
A financially attractive supplier quote is not an executable production plan. Confirm process capability, capacity, tooling ownership, intellectual-property protection, quality approval, and delivery performance.
Test the transition sequence and the fallback plan. Moving all volume before the external process is ready can create a disruption that overwhelms the modeled price advantage.
Consider partial outsourcing, dual capability, or a phased transition when they address a real constraint. These are alternatives to evaluate, not automatic compromises that preserve every cost in both models.
Frequently asked questions
- Are fixed costs irrelevant to make or buy? No. Fixed costs matter when they change because of the decision; an unchanged allocation does not become savings merely because it moves to another cost center.
- Does unused capacity have an opportunity cost? Only when there is a credible alternative use with economic value. Idle hours alone are not evidence of a benefit.
- Should the lowest-cost option always win? No. Required quality, legal obligations, service, strategic capabilities, and unacceptable continuity risks can constrain the choice.
Make the operating case as strong as the financial case
VPP evaluates make-or-buy choices through a shared view of relevant economics, supplier feasibility, and implementation requirements. The objective is a decision that remains defensible after the cost allocations are removed and the transition begins.