IR35 Status Determination: 2026/27 Tax Year Guide
Understand how IR35 status is determined for the 2026/27 tax year. Learn about the new small business thresholds, core legal status tests, and CEST limitations under HMRC rules.
Key Takeaways
- Status Responsibility: If your end client is medium or large, they must determine your IR35 status. If they are a small company, the compliance burden remains with your personal service company.
- New 2026 Thresholds: The small company criteria increased on 6 April 2026 to £15 million turnover, £7.5 million balance sheet, and up to 50 employees.
- The Three Pillars: HMRC assess control, the right of substitution, and mutuality of obligation to decide if a contract represents employment or self-employment.
- Status Determination Statements: A valid Status Determination Statement must include clear logical reasoning. Blanket determinations violate the statutory requirement for reasonable care.
- CEST Tool Limitations: The official Check Employment Status for Tax tool does not evaluate mutuality of obligation, returning "unable to determine" in approximately 20% of assessments.
How do I know if my contract is inside or outside IR35?
To determine whether your contract is inside or outside IR35, you must evaluate whether the working relationship behaves like employment or independent self-employment. An inside-IR35 status means you are treated as an employee for tax purposes, requiring the fee-payer to deduct Income Tax and National Insurance contributions via Pay As You Earn. An outside-IR35 status means you operate as a genuine business, allowing you to pay yourself through a combination of salary and company dividends.
Determining this status requires a thorough analysis of both your written contract and your actual day-to-day working practices. HMRC will look past the contractual labels to see if your working relationship reflects a contract of service as opposed to a contract for services.
What is IR35 and why does status determination matter?
IR35 refers to the UK's off-payroll working rules. These anti-avoidance tax laws ensure that individuals working like employees pay similar taxes to employees, even if they operate through an intermediary company.
These rules are legislated under Chapter 8 and Chapter 10 of the Income Tax (Earnings and Pensions) Act 2003. Accurate status determination matters because incorrect classification exposes businesses and contractors to substantial back-taxes, interest, and financial penalties from HMRC.
Who is responsible for determining your IR35 status?
The party responsible for determining your IR35 status depends on whether your end client is in the public sector, or classifies as a medium-to-large private enterprise versus a small company.
From 6 April 2026, the thresholds for qualifying as a small company increased. If your end client meets at least two of the statutory criteria shown below, they are classified as small and exempt from the off-payroll working rules. When a client is exempt, the legal responsibility for determining IR35 status and paying the correct tax reverts entirely to your personal service company under Chapter 8 of the Income Tax (Earnings and Pensions) Act 2003.
| Client Type & Size | Small Company Thresholds (From 6 April 2026) | Who Determines IR35 Status? |
|---|---|---|
| Public Sector | Not applicable | The end-user public authority |
| Medium or Large Private Company | Meets at least two: Turnover > £15m, Balance Sheet > £7.5m, > 50 employees | The end-user client |
| Small Private Company | Meets at least two: Turnover ≤ £15m, Balance Sheet ≤ £7.5m, ≤ 50 employees | The contractor's Personal Service Company |
Note that the size test is determined by the client's financial data from the preceding financial year. Contractors should request formal written confirmation of their client's size status, which the client is legally required to respond to within 45 days of receipt.
What are the three core IR35 status tests?
HMRC and tax tribunals evaluate employment status using three primary legal tests established by case law. These three pillars assess whether the engagement resembles a contract of service.
Is there a right of substitution in your contract?
A genuine right of substitution means you can send another qualified individual to complete the contracted work instead of yourself. If the client requires personal service, the engagement heavily points towards an inside-IR35 ruling.
- Genuine substitution: The contract explicitly allows substitution, the client cannot unreasonably refuse a competent candidate, and you pay the substitute yourself.
- Personal service requirement: The contract names you specifically as the only person who can do the work, or the client can reject any substitute without reason.
- Practical obstacles: A theoretical right to substitute exists, but you are the only person who holds the necessary security clearances, meaning substitution is impossible in reality.
Who has control over how, when, and where you work?
The control test examines direct supervision. Genuine contractors retain autonomous control over how they complete their assignments, while employees are subject to a master-servant control relationship.
An outside-IR35 engagement is indicated when the client controls only the final deliverable or outcome of the work, and you set your own working hours. If a client can reallocate you to different tasks at their daily discretion, or subjects you to internal performance reviews, this demonstrates the level of control typical of an employment relationship.
Does mutuality of obligation (MOO) exist in your contract?
Mutuality of obligation refers to whether a client is obliged to provide ongoing work and whether you are obliged to accept it. In a genuine contractor relationship, no such reciprocal obligations exist beyond the agreed project scope.
Following the Supreme Court's PGMOL decision in late 2024, the legal interpretation of mutuality of obligation has evolved for the 2026/27 tax year. A basic contractual obligation to perform work in exchange for pay is present in almost all contracts. To demonstrate an outside-IR35 status, the relationship must clearly be project-based with defined delivery terms rather than showing a continuous, open-ended expectation of ongoing work.
What other secondary status indicators does HMRC consider?
HMRC and tax tribunals look at the overall picture of the business arrangement. They will review secondary indicators to establish if you are genuinely in business on your own account.
- Financial risk: Real contractors risk their own capital, purchase professional indemnity insurance, and must correct defective work at their own expense.
- Provision of equipment: Genuinely self-employed individuals usually provide their own specialist tools, software, and hardware rather than relying on client-issued devices.
- Organizational integration: To remain outside IR35, avoid being integrated into the client's business. You should not appear on internal org charts, have staff email accounts that lack contractor labels, or manage permanent staff.
- Business-on-own-account: Operating a business website, marketing your services to the public, and managing multiple concurrent clients all support an outside-IR35 status.
How does the Status Determination Statement (SDS) work?
A Status Determination Statement is a legal document issued by medium or large clients that declares your IR35 status. The client must provide this document, along with detailed reasons for their decision, to both you and the fee-paying agency.
Under the off-payroll working legislation, end clients must use reasonable care when producing an SDS. Issuing blanket determinations, where all contractors are declared inside IR35 without an individual assessment, fails the reasonable care test and leaves the client liable for the relevant payroll taxes.
If you disagree with the determination, you can submit a formal written appeal. The client has 45 days to respond, during which they must either uphold their determination with further explanation or issue a new SDS. If they fail to respond within this time limit, they assume the liability for paying any taxes and National Insurance due.
Should you rely on HMRC's CEST tool?
The Check Employment Status for Tax tool is HMRC's official digital questionnaire designed to help determine IR35 status. HMRC has stated they will stand by CEST results, provided all information entered by the user is completely accurate.
However, the tool has notable historical limitations. CEST does not explicitly test for mutuality of obligation, and it returns an "unable to determine" result in roughly one-fifth of cases. While HMRC updated the tool's interface in April 2025, the underlying logic remains unchanged from 2017, meaning borderline cases require independent assessment.
Your 2026/27 IR35 compliance checklist
To ensure your contract remains safely outside IR35 during the 2026/27 tax year, use this step-by-step compliance checklist to review your contract and working practices.
- Determine the client's size under the 2026 criteria to identify who holds the legal responsibility for the IR35 assessment.
- Review the written contract to ensure it contains explicit rights to provide a substitute, and no clauses granting the client day-to-day managerial supervision.
- Align actual working practices with your contract, ensuring you do not attend internal staff training, have appraisals, or use generic employee email signatures.
- Ensure all assignments are project-focused with clearly defined outcomes, rather than continuous rolling support duties.
- Obtain a valid Status Determination Statement from your client if they are a medium or large company, and verify they exercised reasonable care.
- Collect and archive evidence of your independent business operations, such as business insurances, specialist equipment purchases, and marketing materials.
What happens if my end client is classified as a small company in 2026/27?
If your end client meets the qualifying criteria of a small company, the off-payroll rules under Chapter 10 of ITEPA 2003 do not apply. Instead, the legal responsibility for determining IR35 status, declaring it, and paying the correct taxes reverts back to you as the contractor under Chapter 8 ITEPA 2003.
Can a client issue a blanket inside IR35 determination?
No. Under statutory rules, clients must exercise "reasonable care" when making an assessment. Making a blanket determination across all contractors without reviewing individual contracts and working arrangements represents a failure of reasonable care, which shifts tax liability from the fee-payer back to the end client.
What should I do if I disagree with my client's Status Determination Statement?
You should raise a formal dispute with your client in writing, outlining your detailed reasoning and providing evidence of self-employment. The client is legally required to respond within 45 days. They must either stand by their decision with detailed reasons or issue an amended SDS.
Does HMRC's CEST tool guarantee that my contract is outside IR35?
HMRC will respect the output generated by the CEST tool only if the information entered is accurate and representative of the true working relationships. CEST does not guarantee safety if HMRC find that the actual day-to-day practices do not match the answers provided in the questionnaire.
How did the PGMOL Supreme Court ruling change Mutuality of Obligation?
The ruling clarified that a basic contract containing a mutual commitment to perform work and pay for it is enough to satisfy the initial test of mutuality. For IR35 purposes, the focus must shift to other indicators, looking closely at whether the contract reflects an ongoing, employment-like relationship or a distinct, project-focused business agreement.