What IR35 means for contract engineering teams in 2026

The off-payroll working rules have been part of private-sector life since 2021, and most large energy and infrastructure clients now have a policy, a process and someone who owns it. What varies enormously is how well that process works in practice — whether it supports engagement of scarce contract skills, or quietly obstructs it.

This is a practical overview rather than tax advice. Status is fact-specific and the consequences of getting it wrong sit with real parties, so decisions should always be taken with your own professional advisers. What follows is what we see working operationally across engineering-heavy supply chains.

The mechanics, briefly

Where a worker provides services through an intermediary such as a personal service company, and the client is a medium or large organisation, the client is responsible for determining whether the engagement would look like employment if the intermediary were removed. That determination is issued as a status determination statement, with reasons, to the worker and to the next party in the chain. If the engagement is inside the rules, the fee-payer — often the agency closest to the PSC — operates PAYE and NICs.

Small companies are outside these obligations, in which case the intermediary itself remains responsible for assessing status under the earlier rules. Definitions of what counts as small have moved, so this is worth re-checking rather than assuming a position taken years ago still holds.

One development that has changed the risk conversation is the ability, since April 2024, for HMRC to offset tax already paid by the worker and their intermediary against a client’s liability where a determination is later found to be wrong. That materially reduces the double-taxation exposure that made some clients extremely defensive. It does not remove liability, and it does not remove interest and penalties, but it has taken some of the heat out of blanket caution.

Why blanket determinations backfire

Faced with complexity, some organisations decided every contractor would be treated as inside the rules. It is understandable and it is also a poor outcome. Blanket determinations without reasonable care are not compliant, they push genuinely independent suppliers towards clients who assess properly, and they raise cost for engagements that were never employment-like in the first place.

The practical damage shows up in scarce disciplines. Specialist commissioning, HAZOP chairing, niche safety case work and one-off design packages are exactly the engagements most likely to be genuinely outside — and exactly where losing access to the individual hurts most.

Reasonable care is not a paperwork exercise. It is the difference between a determination that survives challenge and one that transfers liability straight back up the chain.

The factors that actually move the needle

Status turns on the whole picture, but a few factors carry disproportionate weight in engineering contexts.

• Control — who decides how, when and where the work is done. A contractor embedded in a line-managed team on a client rota looks very different from one delivering a defined package to a specification.
• Personal service and substitution — whether a genuine, exercisable right of substitution exists, and whether the contract reflects reality rather than aspiration.
• Mutuality of obligation — whether the client must offer work and the worker must accept it, particularly at the end of a defined scope.
• Financial risk — fixed-price elements, rectification at the supplier’s cost, own equipment, own insurances.
• Integration — line management responsibility, appraisal, internal titles, company benefits, being presented to third parties as part of the client organisation.

The recurring failure is a contract that says one thing and a working arrangement that says another. Determinations are assessed on the actual working practices. If the scope changes — and on projects, scopes always change — the determination should be revisited rather than left to drift.

Supply chain and the wider compliance picture

Off-payroll sits alongside other obligations that engineering supply chains have to manage together: agency conduct regulations, umbrella arrangements and the transparency of deductions within them, right to work checks, and the general expectation that a client can see how the people on its sites are engaged and paid. Non-compliant intermediaries remain a genuine risk, and they tend to surface at the worst moment.

• Determine status role by role, with documented reasoning, before the role goes to market — not after a candidate is selected.
• Keep the SDS, the contract and the actual working practices aligned, and re-assess on material scope change or extension.
• Run a disagreement process that genuinely works and responds inside the statutory window.
• Know every party in the chain between you and the worker, and audit the ones you did not appoint.
• Give clarity early. Candidates make decisions on net position; an unclear status position loses good people to clients who were straightforward about it.

Handled well, off-payroll compliance is simply another part of engaging a contract workforce properly. Handled defensively, it becomes a tax on access to exactly the skills the energy transition is shortest of.