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ir35 for doctors: a practical field guide (uk)

inside vs outside ir35 in plain english: what changed, how to assess engagements, what to ask agencies, and how to avoid accidental disguised employment.

Review date
2026-01-28
Reading time
16 min read
Author
Dr Kola Tytler MBBS CertHE MBA MSt MRCGP
On this page
career toolkitPractical prompts and templates for applications, portfolios and professional development. Check local employer and regulator requirements before use.

The Bottom Line

  • IR35 risk is about the nature of the working relationship, not your job title.
  • Status decisions often hinge on control, substitution, and mutuality of obligation (practically: how ‘staff-like’ you are).
  • Do not choose a structure first. Assess status first, then choose a structure that matches reality.
  • If you use HMRC’s status tools, record your inputs and keep the output as evidence.
  • Avoid ‘blanket’ assumptions. But also avoid magical thinking: if it behaves like employment, treat it as such.

The strategic mistake doctors make

Building a limited company for ‘tax efficiency’ before understanding IR35 status. If the engagement is inside IR35, the efficiency often collapses and complexity rises.

The clinician translation of IR35

IR35 (off-payroll rules) is essentially the tax system asking: “If you removed the intermediary, would this have looked like employment?” Doctor-specific reality: many locum arrangements are operationally staff-like (set rota, supervision structures, fixed processes). That does not mean every engagement is inside IR35 — but it does mean you must assess rather than assume.

How to pressure-test an engagement (doctor edition)

1

1) Control: who decides how the work is done?

If the organisation controls how, when, and where you work in a staff-like way, IR35 risk increases.
2

2) Substitution: can someone else do the work?

Genuine substitution is rare in clinical settings, but understand the contractual and practical reality.
3

3) Mutuality of obligation: is there ongoing obligation?

If you are effectively treated like continuing staff (expected ongoing work), that is a risk signal.
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4) Financial risk and ‘in business on your own account’

Multiple clients, your own insurances, genuine autonomy, and business-like behaviour can be relevant — but it must reflect reality.
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5) Documentation

Keep contracts, booking confirmations, and any status determinations. Evidence beats opinions.

HMRC CEST tool: use it properly (if you use it at all)

If you use HMRC’s CEST tool, treat it like documentation: • Save the output. • Save the inputs you entered. • Ensure the inputs reflect reality, not aspirational framing. If reality changes (e.g., you become staff-like), reassess.
SourceBMA — IR35: how it affects doctors (official professional guidance)
Open Link
SourceGOV.UK — Check Employment Status for Tax (CEST) (official)
Open Link

References

BMA — Tax (IR35 guidance for doctors)
GOV.UK — Check Employment Status for Tax (CEST)