IR35, Authority and Interim Procurement: Why Strong Interims Walk Away

In the UK interim procurement market, there’s a recurring challenge that rarely gets discussed openly.

Organisations struggle to secure the strongest interim procurement professionals — particularly for complex or high-impact assignments.

At the same time, experienced interims are increasingly selective about the roles they accept.

This isn’t a supply issue.

It’s a structural one.

The hidden friction in interim procurement hiring

As explored throughout The Interim Procurement Reality Check, interim procurement outcomes are heavily influenced by how assignments are defined, structured, and supported.

In Part 1 of the series, we looked at how unclear mandates can undermine delivery from the outset.
In Part 2, we explored how urgency can distort hiring decisions.
In Part 3, we examined how focusing on day rates over outcomes can limit commercial return.

There is another layer to this.

IR35 and authority.

IR35: Necessary, but often misunderstood

IR35 has introduced a necessary level of compliance into the UK interim market.

However, in practice, it has also created:

• Caution around how roles are defined

• Uncertainty around decision-making structures

• Reluctance to grant full authority

• Tension between flexibility and compliance

In some cases, roles are shaped more by compliance concerns than by delivery requirements.

That creates a disconnect.

 

Authority: The missing piece

Interim procurement professionals are typically engaged to deliver change quickly.

That might include:

• Leading cost-reduction programmes

• Renegotiating key supplier contracts

• Stabilising supply risk

• Delivering transformation initiatives

All of these require authority.

Yet many interim roles are structured without:

• Clear decision-making rights

• Defined reporting lines

• Senior stakeholder sponsorship

Without authority, delivery slows.
And when delivery slows, value erodes.

Why strong interims walk away

Experienced interim procurement leaders assess opportunities carefully.

They look beyond day rate and contract length.

They consider:

• Is the mandate clear?

• Is there real authority to act?

• Is the organisation aligned internally?

• Is IR35 being handled sensibly?

Where those elements are missing, strong interims often choose not to engage.

Not because the opportunity lacks interest —
but because the likelihood of success is reduced.

The commercial impact of getting this wrong

When organisations struggle to secure the right interim procurement talent, several things can happen:

• Assignments are filled with less suitable profiles

• Delivery takes longer than expected

• Commercial outcomes are diluted

• Internal frustration increases

In many cases, the issue isn’t market availability.

It’s how the role is positioned.

What attracts high-performing interim procurement leaders

Organisations that consistently secure strong interim procurement talent tend to:

• Define clear, outcome-led mandates

• Provide appropriate authority and access

• Align stakeholders early

• Approach IR35 with clarity and confidence

• Treat interim appointments as strategic interventions

This creates an environment where experienced interims can deliver quickly and effectively.

A more balanced approach

IR35 compliance is essential.

But it should not prevent organisations from structuring roles that allow delivery.

The most effective interim procurement assignments balance:

• Compliance

• Clarity

• Authority

• Commercial intent

When that balance is achieved, both organisation and interim benefit.

In summary

The challenge is not a shortage of interim procurement capability in the UK.

It is a shortage of well-structured opportunities.

IR35, unclear authority, and loosely defined mandates can all reduce the likelihood of success — and deter the very interim professionals organisations are trying to attract.

When roles are structured properly, interim procurement leaders remain one of the most effective ways to deliver rapid, measurable impact.

Considering interim procurement support?

The difference between a successful interim appointment and a frustrating one is rarely capability — it’s how the role is defined at the outset.

If you’re currently planning an interim procurement or supply chain hire, we’d be happy to help shape the brief to ensure it delivers measurable outcomes.

Our approach to interim procurement leadership focuses on clear mandates, appropriate authority, and measurable commercial return from day one.

For an initial conversation, feel free to contact Dan Plimmer directly:

 dan.plimmer@jonlee.co.uk
 01384 446174

The interim procurement reality check

• Part 1: Why Interim Procurement & Supply Chain Hires So Often Miss the Mark

• Part 2: Why Rushing Interim Procurement Hires Is Risky

• Part 3: Interim Procurement ROI vs Day Rates in the UK

• Part 4: IR35, Authority and Interim Procurement: Why Strong Interims Walk Away