Supplier selection decision tree template

What the supplier selection decision tree process is

A supplier selection decision tree answers one question: given this requirement, which sourcing route are we entitled to take, and who is entitled to decide it? Every node is a test that can be answered from evidence, every branch is labelled with the answer rather than the next task, and every path ends at a named outcome instead of funnelling back into one happy path. That is what makes it a decision tree and not a process map.

The distinction matters because the two documents get confused. If you need the end-to-end flow (identifying a need, agreeing funding, issuing a tender, awarding, contracting, taking delivery and reviewing supplier performance) use the procurement process flowchart instead. That page answers "what happens next, and who does it". This page answers "which option do we choose, and who chooses it". In practice the decision tree sits inside the route-to-market step of that process map, and it is the part organisations argue about, because it settles whether a competitive tender is required at all. For the separate question of how a supplier gets onto the approved list in the first place, see the vendor approval process.

The chart carries seven decisions across four decision-rights lanes (Requester, Procurement, Technical and compliance, and Finance and risk) and terminates in five distinct outcomes: a direct award to an existing approved supplier, a three-quote comparison, a full competitive tender, a single-source award with a documented justification, and rejection back to the requester for re-specification. The pivotal tests carry notes stating the criteria behind them, because a decision tree is only useful when the thresholds are written down rather than recalled differently by each buyer.

What this flowchart covers

In this template

• Four decision-rights lanes (Requester, Procurement, Technical and compliance, and Finance and risk) across five stages: Requirement, Route to market, Supplier assessment, Cost and risk, and Award decision. The lanes name who answers each question, not who does the work.
• The route-to-market spine in the Procurement lane: "Existing approved supplier?" followed by "Capacity and contract in date?", where a No on either test sends the requirement on to "Spend above tender threshold?" instead of to a direct award.
• The threshold branch, where "Below threshold" terminates immediately at "Run three-quote comparison", and "Above threshold" continues to "Specialist or single source?", whose Competitive branch ends at "Run full competitive tender".
• The single-source arm: the Single source branch records a written justification before anything is awarded, then passes through "Risk assessment acceptable?" to "Award single source with justification", with a note setting out dependency, continuity, financial standing and screening criteria.
• The direct-award arm: "Meets mandatory criteria?" as a pass-or-fail test in the Technical and compliance lane, then "Total cost within budget?" in the Finance and risk lane, whose Over budget branch goes to "Negotiate price or revise scope" and re-tests the same question rather than quietly accepting the price.
• Five distinct endpoints instead of one shared exit: direct award, three-quote comparison, full tender, justified single source, and "Reject and re-specify requirement", which collects both a mandatory-criteria failure and a failed risk assessment.

When to use this template

• Requesters keep asking whether they need three quotes or a full tender, and the answer changes depending on who they ask.
• Your purchasing policy states the thresholds in prose, and you want them drawn as tests with answers attached to each branch.
• Single-source awards are increasing and nobody can point to the test that authorised them or to where the justification is filed.
• You are agreeing decision rights: which questions Procurement answers alone, and which need technical, compliance or finance sign-off before an award.
• An auditor, customer or internal reviewer has asked how suppliers are selected and why a particular award was not competed.

How it works

1. Open the template as a chart

   Open the supplier selection decision tree and use it as a new chart. Nothing is locked: every lane, test, branch label and outcome can be renamed, moved or deleted.

2. Set the thresholds that drive the route

   "Spend above tender threshold?" is where your rules live. Write the value bands into the note: below which figure a single quote is enough, where three quotes start, and where a full tender becomes mandatory. State the currency, and state whether the threshold applies per order or to the aggregate annual value with that supplier, or requirements will be split to stay underneath it. If you are a public body, take the figures and the notice requirements from the procurement regulations you work under rather than from this template.

3. Name who answers each question

   Replace Requester, Procurement, Technical and compliance, and Finance and risk with the roles that actually hold the decision. One lane per decision-maker, not per person, so the chart survives someone changing job. If technical review and compliance sit with different people in your organisation, split that lane in two — it is the lane most often shared by accident.

4. Write the mandatory criteria down as pass or fail

   Put the criteria behind "Meets mandatory criteria?" into its note: technical specification, certification valid for this scope, insurance, and any regulatory or data protection requirement. Keep weighted scoring out of this test. Mixing a pass-or-fail requirement into a scored matrix lets a supplier compensate for a mandatory failure with a good price, which is the single most common defect in a selection decision.

5. Define what a single-source justification must contain

   Name the fields on "Record single-source justification": why no other supplier can meet the requirement, what was done to test that, the value, the duration, and who authorised it. Give each justification an expiry date so it is re-tested at renewal rather than rolled forward, and check that the constraint is genuine rather than created by a specification written around one supplier's product.

6. Agree what each endpoint hands over to

   This chart stops at the route decision. Three quotes, a tender and an award each start their own process, so link "Run three-quote comparison" and "Run full competitive tender" to your procurement process map, and the two award outcomes to the purchase order process, instead of documenting the same steps twice and letting the two versions drift apart.

7. Circulate it and keep one current version

   Share the chart with Procurement, Finance and every approver named in it, capture their approval, and link the approved version from your purchasing policy. Use the version history so that when a threshold changes you can show which rule applied on the date an award was made.

Frequently asked questions

What is a supplier selection decision tree?

It is a diagram of the tests that decide how a supplier is chosen for a given requirement, with the answers written on the branches. Rather than listing sourcing tasks in order, it asks whether an approved supplier already covers the requirement and has capacity, whether the spend sits above the competitive-tender threshold, whether the requirement is genuinely specialist or single-source, whether the supplier meets mandatory technical and compliance criteria, whether total cost of ownership is within budget, and whether risk assessment passes. Each path terminates in a named outcome — direct award, three quotes, full tender, a justified single source, or rejection — so the route is decided by the evidence rather than by whoever is asked.

How is this different from a procurement process flowchart?

A procurement process flowchart is a cross-functional map of what happens next and who does it, from identifying a need through specification, funding, tender, award, contract, delivery and performance review. A decision tree covers a much narrower question: which of several routes this requirement qualifies for, and who is entitled to answer each test. It has more decisions than tasks, its branches carry answers rather than actions, and its paths end at different outcomes instead of rejoining one flow. Most organisations need both — the tree usually sits inside the route-to-market step of the process map.

When do you need three quotes, and when do you need a full tender?

That depends on rules you set and record, not on convention. Most commercial organisations use value bands in a delegation of authority: a single quote below a low threshold, three quotes in a middle band, and a full competitive tender above it, with an exception route for genuine single-source cases. The template leaves the figures blank on purpose, because a threshold copied from another organisation is not defensible. Two details matter as much as the numbers: whether the threshold is measured per order or against aggregate annual spend with that supplier, and who may authorise an exception. Public bodies do not set these figures themselves — the thresholds, publication requirements and standstill rules come from the procurement regulations in their jurisdiction.

What criteria should decide which supplier is selected?

Separate the mandatory ones from the scored ones. Mandatory criteria are pass or fail: the technical specification, certification valid for the scope being bought, insurance, and any regulatory or data protection requirement. A supplier that fails one is not selectable at any price, which is why the chart tests them before cost. Everything else — price, total cost of ownership, lead time, service levels, sustainability — is scored against weightings agreed before bids are opened. ISO 9001:2015 clause 8.4 expects an organisation to determine criteria for evaluating, selecting, monitoring and re-evaluating external providers and to retain documented information on the results, but it prescribes neither the criteria nor the weightings.

When is a single-source award acceptable?

When only one supplier can genuinely meet the requirement — proprietary technology, a compatibility or continuity constraint, or a real emergency — and the reason is documented before the award rather than reconstructed afterwards. The test to apply is whether the constraint is real or manufactured by your own specification, since a requirement written around one product creates its own sole source. In this chart the Single source branch cannot reach an award without passing through a recorded justification and a risk assessment, because a non-competed award has no market price test to fall back on. Give each justification a value, a duration, a named approver and an expiry date.