Sole source vs single source: what the label changes

A sourcing label is useful when it tells you what to do next. Choosing one supplier calls for a purchasing decision; having only one qualified supplier calls for qualification or development work. Record both the market alternatives and the sources you can actually use, then compare the time to change with the time your build can wait.

What is the difference between sole source and single source?

Sole source means only one supplier is currently qualified and able to meet the requirement. Single source means alternatives exist, but the buyer chooses to buy from one. In manufacturing, record the qualification scope and time to switch beside the label: a market alternative cannot protect tomorrow's build if it needs six months of approval work.

These are operational working definitions. Organizations sometimes use the terms differently, and government acquisition uses specific authorities for awards without full competition. Define your categories before comparing risk reports across sites.

The distinction changes the remedy. A single-source commercial choice may be reopened, with orders allocated to another approved supplier. A sole-source condition needs the missing capability, tooling, qualification, customer permission, or design alternative developed first. Sending the same request for quote to more companies will not remove that barrier.

For the detailed execution of a volume split and source qualification, use dual sourcing. This lesson helps you decide which problem that process must solve.

Why can a single-source decision become a sole-source exposure?

Your team may have chosen one supplier when several could make the part. Years later, only the incumbent holds production tooling, runs the current revision, knows the process, or appears on the customer's approved list. The original choice was competitive; the current recovery options are limited.

Distinguish three states: an alternative exists in the market, an alternative has passed your approval path, and an alternative can deliver the required quantity by the need date. None implies the next. A qualified source with no available capacity may protect design continuity while providing little immediate schedule protection.

Approval scope matters. A supplier approved for one site, process, material, or part revision is not automatically approved for all its operations. Check the actual records. For aerospace and automotive parts, ask quality which first-article or production-part approval evidence your contract requires; do not guess a universal requalification rule from the sourcing label.

An illustrative example: Supplier A makes a machined housing. Supplier B has the equipment, but no approved production lot and no access to the casting pattern. Calling the part single source because B quoted previously hides the work remaining. Record A as the only current production source, B as a candidate, and the casting pattern as a separate dependency.

How should you classify each critical part?

Classify at part number, revision, site, and process scope. A supplier can be interchangeable for a standard fastener and irreplaceable for a custom casting. Record market capability, approval status, and delivery availability separately; a company-level vendor count loses the distinctions that determine your recovery options.

Use the following decision record during a sourcing review. Revisit it when the drawing, source, customer approval, production location, or demand changes.

Classify the production-source exposure

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A three-row table distinguishes an approved available alternate, an unapproved market candidate, and no capable market alternative, with a different next action for each.

Evidence state	Production exposure	Next action
Approved independent alternate can meet need date	Single source by allocation choice	Decide allocation and maintain readiness
Capable candidate lacks required approval or tooling	One usable production source today	Complete qualification and remove switching barriers
No other capable source identified	Sole-source development problem	Develop capability, redesign or bridge recovery with agreed protection

Do not turn an unanswered question into a favorable answer. If the sub-tier source or approval status is unknown, record uncertainty and assign a verification action. That produces a better sourcing decision than inventing a second source to complete the report.

How do you decide whether another source is worth qualifying?

Compare the time to restore approved supply with your usable inventory and credible incoming orders. Include all steps in the restoration estimate: supplier selection, tooling, sample production, testing, approval, capacity reservation, production, and transport. A quote lead time rarely covers that entire path.

Suppose a critical housing has four weeks of usable inventory. Your illustrative qualification estimate is fourteen weeks, followed by four weeks of production and delivery. The exposure is not the supplier's ordinary four-week lead time. It is the gap between inventory exhaustion and usable alternate supply, with uncertainty around both dates.

Then compare options. You may qualify another supplier, establish an approved design alternative, hold more inventory, reserve capacity, secure tooling access, or combine these actions. Use costs and dates supplied by your own team. A standard savings percentage or generic risk score does not settle the decision.

A low-volume part may not support two continuous production streams. A larger buffer and a maintained qualification plan may be sensible if the organization accepts the remaining risk. Record why this choice fits the part, the circumstances that would reopen it, and who owns the review.

What evidence belongs in a sole-source justification?

For an internal manufacturing decision, explain the requirement, the alternatives examined, the barrier to substitution, and the action to reduce exposure. Give the remaining qualification work an owner and date. Avoid a justification that says only that the incumbent is familiar or that another qualification would be inconvenient.

A useful short statement is: “Housing H-210 revision C has one approved production source. Two candidates have suitable equipment; neither has an approved casting route. Quality will complete the candidate assessment by the stated date, purchasing will secure pattern access, and the planner will review cover weekly until alternate production is accepted.” This is an illustrative operational record, not a government award justification.

In the United States

FAR 6.302-1 addresses particular government awards where only one responsible source, or certain limited-source situations for named agencies, can satisfy requirements. Its justification and approval rules are separate from a manufacturer's internal sourcing classification. Do not treat an internal sole-source label as permission for a federal award without competition. FAR 6.302-1.

EO 14415 includes sole-source dependence among manufacturing and supply concerns and directs regulatory action on vetting. Prepare evidence of the dependency and mitigation; determine the actual contractor duty from applicable implementation and contract requirements. EO 14415, Sections 3 and 7(e).

In the United States

For US medical devices, FDA's change guidance includes supplier material processing or finishing changes in its materials-change assessment. A supplier change is not an automatic requirement for a new 510(k); the device manufacturer must assess the change and its effects through the applicable decision process. FDA, Deciding When to Submit a 510(k), materials flowchart C2.

How do you check that alternatives reduce the exposure?

Count independent supply paths, not names on purchase orders. Two distributors of the same manufacturer's component may offer different inventory and service while retaining one manufacturing dependency. Two machining suppliers can share the same casting house, heat treater, or customer-owned tool.

Record that dependency before committing to qualification spending. An alternate that bypasses the incumbent machine shop but uses the same casting route solves a machining outage. It does not solve a casting outage. Both improvements may be worthwhile, provided the business understands what each protects.

Use supply concentration risk to compare shared nodes and geography. Follow supplier risk assessment to connect the finding to the affected builds and the action owner. Recheck the classification after the first accepted alternate production lot, rather than marking the risk closed when a quote arrives.

What questions do teams ask about sourcing classifications?

The sourcing label should explain the work needed to protect production. Teams often need to separate an original purchasing choice from today's usable alternatives, then decide whether qualification is worthwhile. These answers keep approval, delivery readiness, and accepted exposure visible alongside the classification.

Can a part be single source commercially and sole source operationally?

Yes. Your team may have chosen the incumbent, while the current alternate still needs tooling or approval. Record both the original choice and current production readiness so the corrective work is clear.

Does a second supplier on the approved list count as protection?

Only to the extent its approval is applicable and it can supply when needed. Check revision, site, process, available capacity, and recent production evidence. Keep qualification status and recovery availability in separate fields.

Should every sole-source part be dual sourced?

No universal rule settles that decision. Focus on build impact, recovery time, qualification feasibility, demand, and cost. Document the chosen protection and residual exposure instead of enforcing a vendor-count target.

Start with the parts whose loss would stop production. Give each a sourcing classification, a dated evidence record, and an owner for its unresolved barrier. If the follow-up work is difficult to keep current, talk to our team.

This article is general information, not legal or tax advice. Check how the rules apply to your business with your legal or tax advisor.

Sources (3)

1. FAR
2. EO
3. FDA