IR35 and contractor screening in AI hiring

MatchCard · 21 July 2026 · 6 min read

Quick answerIR35 status in the UK is determined by the actual working pattern of an engagement, not the contract wording: control, substitution rights, mutuality of obligation, and integration into the client's team are the core factors. Since 2021, medium and large private-sector clients, not the contractor, are responsible for making that determination.

Most hiring assessments are built around one question: is this person good at the job? For a contractor role, that's not the only question that matters. How the role is actually structured, who controls the work, whether the contractor could genuinely send a substitute, how integrated they are into the team, determines whether HMRC would view the engagement as employment in disguise. Almost nobody screens for that at the hiring stage. It usually surfaces later, in a contract review or an HMRC enquiry, by which point the working pattern is already established.

Who actually decides IR35 status now

Since April 2021, for medium and large private-sector clients, responsibility for determining a contractor's IR35 status sits with the client, not the contractor's own limited company. The client must issue a Status Determination Statement and take reasonable care in reaching it. Small clients, as defined under the Companies Act 2006, are exempt from this shift, and the contractor's company remains responsible for its own determination in that case.

That responsibility shift is exactly why it belongs earlier in the process than it currently sits. A status decision made properly at the point of engagement is a documented, defensible judgement. The same decision made retroactively, after months of a working pattern that looks a lot like employment, is a much more expensive conversation.

What actually determines status

No single factor is decisive; HMRC assesses status on the working reality, not the contract language. The five core factors, weighted roughly in the order that investigators and tribunals typically rank them, are far more useful than any contract clause for predicting what HMRC would decide:

• Control. How much the client dictates how, when, and where the work gets done, versus the contractor deciding their own method and schedule.
• Substitution. Whether the contractor could genuinely send a qualified substitute to do the work in their place, and whether the client would actually accept one.
• Mutuality of obligation. Whether the client is obliged to keep offering work and the contractor obliged to accept it, closer to an ongoing employment relationship than a discrete engagement.
• Integration. Whether the contractor is managed, appraised, and embedded like an employee: a line manager, a fixed desk, inclusion in staff processes and communications.
• Financial risk. Whether the contractor bears genuine business risk (their own equipment, the possibility of a loss on a fixed-price piece of work) rather than simply being paid for time.

Why this belongs in the hiring conversation, not just the contract

Most of these factors are set by decisions made before an offer goes out: how the role is scoped, whether the person is expected to attend daily standups like an employee, whether a genuine right of substitution is written in and would actually survive being exercised. By the time the contract is drafted, the working pattern that determines status has usually already been decided informally, in the interview, in the job description, in what the hiring manager promises about "how the team works." A hiring process that never asks these questions is quietly making an IR35-relevant decision without anyone noticing they made one.

This connects to a wider pattern worth reading in full: what a mismatched hire actually costs, once replacement, lost time, and management overhead are counted. An engagement that turns out to be IR35-caught after the fact adds a category of cost most of that breakdown doesn't even cover: backdated tax liability and penalties, on top of everything else.

Where AI hiring assessment fits

Compared with personality tests, skills assessments and ATS keyword screening, none of which touch employment status at all, an assessment built for mutual fit hiring can surface working-pattern questions at the same point it surfaces salary and role-fit questions: does the engagement genuinely allow substitution, is the expected level of day-to-day control consistent with a contractor relationship, does the role as described match a status the client can defend. That doesn't replace a formal status determination. It means the factors that feed one are on the table before an offer is made, not discovered afterward.