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Reports and quality

The trial period for a new supplier

Six months to find out whether they work, with criteria decided before starting.

Updated on 13/08/2026

A new supplier almost always comes in on price or urgency, and their evaluation is left to the general impression of whoever deals with them most. Six months later nobody can say whether they work better or worse than the previous one, because nobody decided in advance what would be looked at.

The four criteria that suffice

CriterionHow it is measuredWhen to worry
Meets deadlinesOn-time deliveries over the totalIf it worsens after the first deliveries
Meets specificationQuality incidents per deliveryAny repeat of the same defect
Responds on documentsDays to supply what is requestedMore than a week on average
And warns when something is wrongHow many problems they told you before you saw themIf the answer is zero

Important

The fourth is not measured in numbers and best predicts how the relationship will go. A supplier who warns of a delay three days ahead is worth more than one who hits 98% and tells you about the 2% when the lorry does not arrive.

How to run the period

  1. 1

    Write the criteria before the first delivery

    Four, with thresholds. Written afterwards, they get written to justify the conclusion you already had.

  2. 2

    Record incidents as they happen

    In their file, not in the memory of whoever suffered them.

  3. 3

    Review at three months, not only at the end

    That is when it can still be corrected; at the end you only decide.

  4. 4

    And close with a written decision

    Approved, approved with conditions, or not. All three are valid answers.

Watch out

The awkward case is the supplier who performs but is hard to work with. If that is not among the criteria, the decision will still be taken on that basis, only without being explainable — and that conversation with the supplier cannot then be had.

What makes the period useful

The first changes the outcome most: a supplier who knows they are being evaluated, and how, behaves differently — and that is information about them too.

Worth knowing

The same scheme suits an external collaborator, a subcontractor or an advisory firm. What is measured in criterion two changes; the other three are identical.

Always six months?

Long enough for ten or twelve deliveries. Two tell you nothing.

What if they fail on the first delivery?

Record it and raise it; one bad delivery does not decide, repeating it does.

Is formal approval required?

It depends on your quality scheme; a written decision is worth having anyway.

A real case

The situation

A company brings in a supplier on price and six months later argues about keeping them.

What you do

  1. Writes four criteria before the first delivery
  2. Reviews at three months and raises two incidents

What you get

The final decision is made on data and the supplier knew from the start what was being measured.

The situation

A new supplier enters a trial period and nobody defines what will be looked at.

What you do

  1. Sets what will be measured and for how long
  2. Records every delivery and every incident
  3. Reviews at the end with the data in front of you

What you get

The decision to continue is taken on facts rather than an impression.

The situation

The period ends and nobody decides anything.

What you do

  1. Sets a review date at the start

What you get

The trial period genuinely ends.

The situation

Continuing is decided by inertia.

What you do

  1. Checks the record before deciding

What you get

The decision is taken on a basis.

The situation

The supplier does not know they are on trial.

What you do

  1. Tells them and shares what will be measured

What you get

The supplier gets a chance to succeed.

The situation

The supplier is dropped and there is no record of why.

What you do

  1. Records the reason for closing

What you get

The decision is explicable months later.

This article answers

  • approving a new supplier
  • supplier trial period
  • criteria to evaluate a supplier
  • when to stop working with a supplier