IR35 for locum doctors

Locum medicine has an IR35 problem that most sectors do not: a great deal of what looks like client control is actually clinical governance and statutory regulation. Being required to follow a trust's protocols is not the same as an employer directing how you work — but it is very easily recorded as though it were.

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Why it is contested

What actually decides it for locum doctors

Public-sector bodies, including NHS trusts, must make the status determination for engagements they run, and blanket determinations across whole locum cohorts have been a recurring complaint since the 2017 reforms. That matters because the honest analysis is genuinely fact-sensitive: a locum filling a fixed rota slot in a department's normal staffing, week after week, sits very differently from one brought in for a defined piece of work such as clearing a specific waiting-list backlog. Control needs separating carefully from regulation before either conclusion is safe.

Job titles decide nothing. There is no such thing as a role that is inherently inside or outside IR35. Status turns on the facts of a particular engagement, which is why two locum doctors on the same rate at the same client can land on opposite sides of the line.

The five HMRC factors

How each factor tends to play out

Including mutuality of obligation, which HMRC's own CEST tool leaves out despite the Supreme Court confirming its relevance in PGMOL.

Personal service & substitution

This is usually the hardest factor in medicine. Practising privileges, GMC registration, credentialing and trust onboarding are personal to you, so a genuine right to send a substitute is rare — and where it is absent, that points toward employment.

Control

Separate clinical governance from managerial control. Following infection-control policy or a trust's prescribing formulary is regulation. Being allocated to whichever ward needs cover, with your hours set by someone else's rota, is control of a different kind.

Mutuality of obligation

Ad-hoc shift-by-shift booking, where you are free to decline and the trust is free to stop offering, is weak mutuality. A block booking that guarantees a fixed number of sessions over months, which you are expected to work, is much stronger and points inside.

Financial risk

Carrying your own medical indemnity cover rather than relying solely on trust indemnity is meaningful. Being paid a fixed hourly rate for hours attended, with no exposure to the cost of putting anything right, is not.

In business on own account

Working across several trusts or practices, holding your own indemnity, funding your own CPD and equipment, and taking private work alongside all point to a business. Being embedded in one department's rota for years does not.

Signals to check

Which way does your engagement point?

Tends toward outside

You are engaged for defined sessions or a specific piece of work, such as a named backlog or clinic list
You accept or decline individual shifts freely, with no obligation on either side between bookings
You work across several trusts, practices or private providers
You hold and fund your own medical indemnity cover and CPD
You are not part of the department's internal staffing structure, appraisals or on-call rota

Tends toward inside

You fill a fixed rota slot as part of the department's normal establishment
You are block-booked for a long, guaranteed period and expected to work it
You are line-managed like substantive staff, including appraisal and mandatory training
You take part in the standard on-call and cover arrangements
You have worked the same post continuously for a long period with no defined endpoint

These are indicators, not a scoring system — no single signal decides status, and a case is judged on the overall picture. The free check weighs all five factors together and tells you how confident it is.

Get my five-factor verdict

Locum doctor IR35 questions

Does following NHS trust protocols mean I am under their control for IR35?

Not automatically. IR35 asks about control exercised by a client over how you do the work; clinical governance, GMC obligations and statutory safety requirements apply to you regardless of who engages you, and would apply to a genuinely independent practitioner too. The distinction to draw is between requirements imposed by regulation and professional standards, and direction imposed by the trust as an employer would — allocating your ward, setting your hours, deciding your caseload.

My trust issued a blanket inside-IR35 determination for all locums. Is that allowed?

A client must take reasonable care in making a determination, and applying one outcome across a whole group without considering individual engagements has been widely criticised for falling short of that. You can dispute a determination through the client-led disagreement process, and the client must respond with reasons. A documented, factor-by-factor assessment of your own engagement is what makes that challenge credible, which is what our report is designed to give you.

I cannot send a substitute because of GMC registration and credentialing. Am I automatically inside IR35?

No, but it removes what is often the strongest single argument for outside status, so the remaining factors have to carry more weight. Personal service is one of several factors rather than a decisive one on its own. Where substitution is genuinely impossible, the analysis turns on control, mutuality of obligation, financial risk, and whether you are in business on your own account — which is why a full five-factor assessment matters more, not less, in medicine.

For the full picture — the three-limb test, the case law and how determinations work — read the complete IR35 guide.

Other roles

IR35 for IT contractors IR35 for management consultants IR35 for interim managers

Find out where you actually stand

Ten plain-English questions about how you really work. A clear inside or outside verdict with the reasoning behind it, in minutes — free, no card and no login.

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Nebula is decision-support, not tax or legal advice, and no IR35 determination is legally binding — not even HMRC's own CEST. Borderline results are flagged with a recommendation to have a qualified IR35 specialist review them.