Single source vs sole source, and when each one is justified.
Both mean buying from one supplier without a competitive RFQ. The difference is whether other suppliers exist. Here is how to tell them apart, how to justify each, and when to run an RFQ instead.
What is the difference between single source and sole source?
Sole source means only one supplier in the market can provide what you need, for example the original manufacturer of a spare part, the holder of a patent or the only licensed distributor in a country. There is no competition to run. Single source means several suppliers could provide it, but you choose one on purpose, for example to keep equipment standard across sites, to protect a tested quality, or because of a genuine emergency.
The difference matters because single sourcing is a choice that gives up competition, so it needs a stronger reason and a regular check against the market. A sole source purchase should still be documented, because the claim that nobody else can supply is a fact you must be able to show. In both cases most procurement policies ask for a written justification before the order is placed.
Single source vs sole source in one table.
The same question asked six ways. The answer always comes back to whether another supplier exists.
| Question | Single source | Sole source |
|---|---|---|
| How many suppliers could supply | Several | Only one |
| Who limits the choice | The buyer, by decision | The market: there is no alternative |
| Typical reasons | Standardization, compatibility with existing equipment, proven quality, a genuine emergency | Patent or proprietary product, original equipment spare parts, an exclusive distributor, unique expertise |
| Is competition possible | Yes, but it is deliberately not used | No |
| Main risk | Paying above market and depending on one supplier out of habit | Little leverage on price and lead time |
| How to control it | A written justification, a periodic RFQ to test the market, a price benchmark | A written justification with evidence, negotiated terms, a search for equivalents at each renewal |
When each one is the right call.
And when the honest answer is to run an RFQ.
Sole source is justified when
- Only the original manufacturer makes the part, or the design is protected by a patent
- One distributor holds the exclusive rights for your country
- Another product would void a warranty or a certification
- You searched for equivalents and can show that none exist
Single source is justified when
- Standardizing on one brand cuts spare parts, training and maintenance across sites
- A supplier's quality has been tested and a change would mean requalification
- A genuine emergency leaves no time for a full RFQ, and it is documented as such
- Volume with one supplier earns terms that splitting the order would lose
Run an RFQ instead when
- Other suppliers exist and nobody has asked them for a price recently
- The reason for one supplier is habit, not a documented requirement
- The item is a standard product sold by several distributors
- Prices have moved and the current supplier has not been tested against the market
How to justify a single or sole source purchase, in four steps.
The same four parts satisfy most procurement policies and most auditors.
- 1
State the need and why only one supplier
Describe the item, the quantity and the requirement that limits the choice: a part number, a compatibility constraint, a certification or a deadline.
- 2
Show the market check
For sole source, record where you searched for alternatives and what you found. For single source, record which other suppliers exist and why they were not chosen.
- 3
Test the price
Without competition, compare the offer with past prices, published price lists or a quotation for a similar item, so the price is not accepted blind.
- 4
Approve, file and set a review date
Have the justification approved under your policy, file it with the purchase order, and set a date to test the market again, for example at contract renewal.
Where this page stops.
Rules on single and sole sourcing differ by organisation and by country. These are the limits.
- Public sector buyers follow their own procurement law, which defines when a direct award is allowed and how it must be published. Check the rules that apply to you.
- A justification is not a formality. If the reason does not hold up, auditors treat the purchase as an unjustified direct award.
- Sole source today is not sole source forever. Patents expire and new distributors appear, so check again at each renewal.
- PROCAI helps with the market check. It searches for suppliers, sends an RFQ from your own mailbox and compares the replies. The decision and the justification stay with your team.
Single and sole sourcing, answered.
What is sole sourcing in procurement?
Sole sourcing is buying from the only supplier able to provide an item or service, because no other source exists, for example the original manufacturer of a spare part or the holder of a patent. Because competition is not possible, procurement policies usually require a written justification showing that the market was checked and no alternative was found.
What is single sourcing in procurement?
Single sourcing is choosing one supplier on purpose when others could also supply, for reasons such as standardization, proven quality, compatibility or urgency. It is a deliberate decision to give up competition, so it should be justified in writing and tested against the market from time to time.
Is single sourcing the same as sole sourcing?
No. In sole sourcing only one supplier exists. In single sourcing several exist and you choose one. The two terms are often mixed up, which is why many procurement policies define both terms separately and ask for different evidence before either kind of purchase is approved.
What are the risks of single sourcing?
Dependence on one supplier for delivery and capacity, less pressure on price, and exposure if that supplier has a disruption. Teams reduce the risk with a documented reason, agreed terms, a backup supplier identified in advance and a periodic RFQ to check the price.
What should a sole source justification include?
A description of the need, the reason only one supplier can meet it, the evidence of the market search, how the price was judged reasonable, and the approval your policy requires. Keep it on file with the purchase order, so an auditor can follow the decision later.
How does PROCAI help with single and sole sourcing?
It makes the market check fast. Describe the item and PROCAI searches for suppliers in up to 3 countries, so you can show whether alternatives exist. If they do, send one RFQ to the shortlist from your own mailbox and compare the quotations side by side. Sending RFQs never costs credits, and the Free plan needs no card.
Check the market before you commit to one supplier.
Find who else can supply, send one RFQ to the shortlist and compare the quotations. Free plan, no card.