What Is IR35?
IR35 is the informal name for the UK government's off-payroll working rules, originally introduced in 2000 and significantly reformed in 2017 and 2021. The legislation targets what HMRC calls "disguised employment" - situations where a worker operates through an intermediary (typically a limited company) but in substance works like an employee of the end client.
If IR35 applies to a particular engagement, the worker's income from that engagement is treated as employment income for tax purposes. This means the worker - or their client - pays income tax and National Insurance Contributions at employment rates, rather than the lower rates available to genuinely self-employed workers.
Does IR35 Apply to Dental Nurse Locums?
Whether IR35 applies depends on several factors, including how you are engaged and how you work.
Sole Traders and PAYE Workers
If you operate as a sole trader (the most common arrangement for dental nurse locums) or work through an umbrella company that puts you on PAYE, IR35 does not apply in the same way. Sole traders pay income tax through Self Assessment, and the off-payroll rules are generally less relevant.
Limited Company Directors
If you operate a Personal Service Company (PSC) - your own limited company through which you invoice practices - IR35 may apply. Since April 2021, large and medium-sized clients (practices) are responsible for assessing IR35 status for engagements they have with workers operating through PSCs. For small dental practices (which most are), the determination responsibility remains with the worker's PSC.
The Three Key Tests
HMRC assesses IR35 status using three key factors:
1. Substitution - Can you send a substitute to do your work? If you can genuinely send another qualified dental nurse in your place (and the client would accept this), this points away from employment and away from IR35.
2. Control - Does the practice control how, when, and where you work? If the practice dictates your start time, your methods, and your daily schedule in the same way it would an employee, this points towards employment (and IR35).
3. Mutuality of Obligation - Is the practice obliged to offer you work, and are you obliged to accept it? If there is no commitment on either side beyond the individual engagement, this points away from employment.
Most dental nurse locums who work on a shift-by-shift basis with no ongoing obligation to a single practice will find that IR35 is less likely to apply. However, a locum who works exclusively at one practice for an extended period, following that practice's instructions and unable to send a substitute, is at greater risk of being inside IR35.
Practical Steps for Locum Dental Nurses
Use HMRC's CEST Tool
HMRC's Check Employment Status for Tax (CEST) tool allows you to answer questions about your working arrangements and receive a determination of your likely employment status. This is not legally binding but is a useful starting point: https://www.gov.uk/guidance/check-employment-status-for-tax
Seek Specialist Advice
A healthcare-specialist accountant who understands the dental locum market will be the most valuable investment you make in your locum career. They can advise on your trading structure, ensure you are paying the correct taxes, and help you document your working arrangements to support an IR35 assessment.
Keep Good Records
If your status is ever questioned by HMRC, contemporaneous records of your working arrangements - including written contracts with each practice that reflect genuine self-employment - will be essential.
Self-Assessment for Sole Trader Locums
Most dental nurse locums operating as sole traders will complete a Self Assessment tax return each year, declaring their locum income, allowable business expenses, and paying income tax and Class 4 National Insurance on their profits. Allowable expenses for locum dental nurses may include:
How NetworkDental Helps
NetworkDental is designed for self-employed locum dental nurses. Each nurse sets their own hourly rate, accepts shifts on their own terms, and works across multiple practices - which supports a genuine self-employment position. Payments are processed through the platform with clear transaction records that support your Self Assessment return. NetworkDental does not direct how you work at a practice - we connect you, and then you work professionally within the practice's clinical environment as an independent contractor.
Start building your self-employed locum income on NetworkDental. Register as a nurse →
