IR35 for Dental Associates: What the 2025/26 Rules Mean for Your Tax Status

What Is IR35 and Why Should Associate Dentists Care?

IR35 is the tax legislation that targets "disguised employment", people who work through their own limited company but would be classed as employees if they were engaged directly. For associate dentists, the question is whether you are genuinely self-employed or whether HMRC would view you as a deemed employee of the practice.

The distinction matters because it changes how much tax and National Insurance you pay. A self-employed associate pays Class 4 NI at 6% on profits between £12,570 and £50,270, and 2% above that. An employee pays 8% employee NI on the same band plus 15% employer NI from the practice. If HMRC decides you are inside IR35, the practice must deduct PAYE and NI from your fees, even if you invoice through a limited company.

In 2025/26, the rules have not changed from the off-payroll working reforms introduced in April 2021 for medium and large clients. But HMRC continues to scrutinise dental associate arrangements, particularly in NHS practices where the degree of control exercised by the practice can be high.

How Does IR35 Apply to Associate Dentists?

Associate dentists typically work under a contract for services, not a contract of service. The BDA model associate agreement is designed to support self-employed status. But as the system prompt notes, the paperwork alone does not determine your status. HMRC and tribunals look at the actual working practice.

The key tests HMRC applies are:

• Control: Does the practice dictate when, where, and how you work? Can you refuse patients or treatments?
• Substitution: Can you send a qualified locum in your place without the practice's consent being unreasonably withheld?
• Mutuality of obligation: Is the practice obliged to offer you work, and are you obliged to accept it?
• Financial risk: Do you bear the risk of non-payment, cover your own costs (lab fees, materials, indemnity), and have the potential to profit from efficient working?
• Integration: Are you part and parcel of the practice, or are you running your own business within it?

For associate dentists, the most common battleground is control. If the practice sets your hours, requires you to attend practice meetings, dictates which treatments you provide, or treats you like a member of staff, HMRC may argue you are an employee in all but name.

NHS IR35 Risks for Associates

NHS associates face particular challenges. The NHS contract imposes obligations on the practice that can filter down to associates. For example, the practice must ensure UDA targets are met, which may lead to pressure on associates to work set sessions or see a minimum number of patients. If the practice controls your patient list, your appointment book, and your clinical schedule, the control test starts to look unfavourable.

That said, many NHS associates remain genuinely self-employed. The key is to structure the arrangement so that you have real independence. You should be able to refuse patients, choose your own treatment methods (within GDC and NHS guidelines), and arrange your own cover when you are away.

HMRC's guidance on off-payroll dental working (ESM3000 series) makes clear that the facts of each case determine the outcome. There is no blanket rule that NHS associates are inside or outside IR35.

The Off-Payroll Dental Rules: Who Decides Your Status?

Since 6 April 2021, the off-payroll working rules (often called IR35 reforms) apply to medium and large clients. For associate dentists working through a limited company, the practice must determine your IR35 status and issue a Status Determination Statement (SDS). If the practice is small (meeting two of: turnover under £10.2m, balance sheet under £5.1m, fewer than 50 employees), the responsibility stays with your limited company.

Most dental practices with multiple associates and staff will be medium or large under these criteria. That means the practice, not you, decides whether you are inside or outside IR35. If they decide you are inside, they must deduct PAYE and NI from your fees before paying your company. This can significantly reduce your net income.

If the practice gets the determination wrong, HMRC can pursue the practice for unpaid tax and NI, plus penalties and interest. This creates a tension: practices may be cautious and default to inside-IR35 determinations to avoid liability, even where a genuine self-employed arrangement exists.

What to Do If Your Practice Issues an Inside-IR35 Determination

If your practice decides you are inside IR35, you have options. First, review the Status Determination Statement. The practice must provide reasons. If you believe the determination is wrong, you can challenge it. The practice must respond within 45 days. If they do not, you can escalate to HMRC.

Second, consider whether your working arrangements can be restructured. Can you introduce more substitution rights? Can you reduce the practice's control over your schedule? Can you take on more financial risk, such as paying for your own materials or lab fees? These changes can shift the balance back towards self-employment.

Third, if the determination stands, you may need to negotiate a fee increase to compensate for the additional tax and NI that will be deducted. A typical inside-IR35 arrangement means your company receives fees net of employer NI (15%) and apprenticeship levy (0.5%), and you pay employee NI and income tax through payroll. Your net take-home can drop by 20-30% compared to a genuine self-employed arrangement.

Practical Steps to Protect Your Self-Employed Status

If you want to stay outside IR35, your working arrangements must reflect genuine self-employment. Here are practical steps associate dentists can take:

• Use a robust contract: The BDA model associate agreement is a good starting point, but it must reflect your actual working practice. Do not use a contract that says one thing while you operate differently.
• Maintain substitution rights: You should be able to send a qualified locum when you are unavailable, without the practice's consent being unreasonably withheld. If the practice insists on approving every locum, that weakens your case.
• Control your own schedule: You should decide when you work, how many sessions you do, and which days you take off. If the practice dictates your hours, you look like an employee.
• Bear financial risk: Pay for your own indemnity, GDC registration, CPD, and professional subscriptions. If the practice reimburses these, it suggests employment.
• Do not receive employee benefits: Holiday pay, sick pay, pension contributions, and other employee benefits are strong indicators of employment. If you receive them, you are almost certainly inside IR35.
• Keep separate business records: Maintain your own bank account, accounting records, and business insurance. Treat your associate work as a business, not a job.

For a detailed breakdown of how these factors apply to your specific situation, read our Associate Tax Survival Guide.

What About Locum Dentists and IR35?

Locum dentists face similar IR35 risks, but the analysis is slightly different. Locums typically have less integration into the practice and more control over when and where they work. However, if a locum works exclusively for one practice over a long period, HMRC may argue that the arrangement has become one of employment.

The off-payroll rules apply to locums working through limited companies in the same way as associates. If the engaging practice is medium or large, it must determine IR35 status. Many locums find that short-term, ad-hoc engagements fall outside IR35, while regular, structured arrangements may be inside.

If you work as a locum through a limited company, you should review each engagement separately. A pattern of working for the same practice every week for months on end is a red flag. Our locum dentist tax services page covers this in more detail.

IR35 and the NHS Pension Scheme

A common concern is whether being inside IR35 affects your NHS Pension Scheme membership. The answer is nuanced. If you are genuinely self-employed, you can still be a member of the NHS Pension Scheme as a locum or associate, provided you meet the scheme's eligibility criteria. Being inside IR35 does not automatically make you an employee for pension purposes.

However, if HMRC reclassifies you as an employee, the practice may be required to pay employer pension contributions on your behalf. This can create complications with the NHS Pension Scheme, which has specific rules about who can join and how contributions are calculated.

If you are concerned about your pension position, speak to a specialist dental accountant who understands both IR35 and the NHS Pension Scheme. Our dental accountants team can help you navigate these issues.

What Happens If HMRC Investigates Your IR35 Status?

HMRC can investigate your IR35 status at any time, but they typically focus on cases where the facts suggest disguised employment. If HMRC decides you are inside IR35, they will issue a determination for unpaid tax and NI, plus interest and potentially penalties.

The liability can be significant. If you have been treated as self-employed for several years but HMRC decides you were an employee, you could face a tax bill running into tens of thousands of pounds. The practice may also be liable for employer NI and penalties if they failed to make a correct determination.

To reduce the risk of an investigation, keep clear records of your working arrangements. Document your substitution rights, your control over your schedule, and your financial independence. If you have a contract that accurately reflects your working practice, that is your strongest defence.

Key Takeaways for 2025/26

• IR35 status is determined by facts, not paperwork. Your actual working practice matters more than your contract.
• NHS associates face particular scrutiny because of the control practices exercise over UDA targets and patient lists.
• Since April 2021, medium and large practices must determine IR35 status for associates and locums working through limited companies.
• If you receive an inside-IR35 determination, you can challenge it or restructure your arrangements.
• Maintain genuine self-employment indicators: substitution, control, financial risk, and no employee benefits.
• HMRC investigations can result in significant back-tax bills. Prevention is better than cure.

For a full assessment of your IR35 position, speak to a dental-specialist accountant. We work with associate dentists across the UK to structure their affairs tax-efficiently while staying compliant. Contact us for a confidential discussion.