Navigating the complexities of the off-payroll working rules (commonly known as IR35) requires a clear understanding of where legal responsibility sits. Following the comprehensive reforms introduced in the private sector, the employment status landscape changed significantly. Today, the rules across both the public and private sectors are aligned, placing the administrative and financial compliance burden firmly on the organisations engaging flexible talent.
For corporate leaders across HR, finance, procurement, and the board, managing contingent workforce risk is a critical operational priority. Understanding who is legally required to make the status assessment is the first step toward building a robust, compliant IR35 process.
Who is responsible for determining IR35 status?
In most engagements, the responsibility for determining whether it falls inside or outside IR35 lies with the end client. The end client is the hiring business or organisation that engages the contractor.
If the contractor is sourced through a recruitment agency or a consultancy, the end client still retains the legal obligation to assess the status. This is because the hiring organisation is best placed to evaluate the day-to-day working practices and the specific contractual terms of the engagement.
There are only two main exceptions where the hiring business does not determine the status:
- When the end client qualifies as a small business under statutory UK criteria.
- When the end client is based entirely overseas with no physical or legal presence in the UK.
What is the small business exemption under IR35?
The off-payroll working rules apply to all public sector organisations and to medium and large businesses in the private sector. However, the legislation provides an exemption for small private sector businesses.
According to the Companies Act 2006, a business qualifies as a small company if it meets at least two of the following criteria (for financial years that begin on or after 6 April 2025):
- An annual turnover of no more than £15 million.
- A balance sheet total of no more than £7.5 million.
- 50 or fewer employees on average.
If the hiring business meets these criteria, the off-payroll rules do not apply to them.
Who determines IR35 status if the client is a small business?
When a hiring business qualifies for the small company exemption, the responsibility for determining IR35 status shifts back to the contractor. In these scenarios, the worker's limited company (often called a personal service company, or PSC) must evaluate the contract and working practices.
If the contractor determines that the assignment is inside IR35, their own limited company is responsible for calculating, deducting, and paying the relevant Income Tax and National Insurance contributions to HMRC.
What is a Status Determination Statement (SDS)?
A Status Determination Statement (SDS) is a formal document that the end client should produce when making an IR35 assessment. The legislation states that an assessment is not legally an SDS until the criteria have been met:
The SDS must meet two legal conditions:
- It must declare the final IR35 status decision, stating whether the engagement is inside or outside IR35.
- It must provide detailed, reasoned conclusions explaining how the decision was reached.
The hiring organisation is legally required to pass this statement down the supply chain. It must be provided directly to the contractor and the next party in the labour chain, typically the recruitment agency. If the client fails to issue the SDS, they assume the role of the deemed-employer and become liable for any unpaid tax and National Insurance.
How does recruitment agency involvement affect IR35 payments and tax deductions?
When a recruitment agency or employment business sits between the end client and the contractor, the flow of funds and compliance duties change. The responsibilities depend heavily on whether the small business exemption applies.
Scenario 1: The client is a medium or large business
When the hiring organisation is a medium or large business, the process follows these distinct steps:
- The end client assesses the assignment and issues the Status Determination Statement.
- The client passes the SDS to the recruitment agency and the contractor before the work begins.
- If the determination is inside IR35, the recruitment agency becomes the deemed employer.
- Before paying the contractor's limited company, the agency must deduct PAYE Income Tax and employee National Insurance contributions. The agency must also pay employer National Insurance contributions to HMRC.
- The agency remits the net amount to the contractor's limited company.
Scenario 2: The client is a small business
When the hiring business is small, the mechanics shift:
- The end client pays the recruitment agency the gross agreed amount for the work completed.
- The agency passes the gross amount directly to the contractor's limited company without making any tax deductions.
- Because the exemption applies, the contractor's limited company is responsible for assessing the IR35 status.
- If the assignment is deemed inside IR35, the contractor's limited company accounts for the taxes by making a deemed employment payment to the worker, ensuring the correct tax and National Insurance are paid to HMRC.
What were the key changes introduced to private sector IR35 rules?
The off-payroll reforms completely altered the compliance landscape for the private sector. The core changes designed to shift compliance accountability include:
- Shifting the Burden: Responsibility for assessing employment status shifted from the individual contractor's PSC to the medium and large end clients engaging them.
- Fee-Payer Liability: The entity closest to the contractor in the supply chain, usually the recruitment agency, became responsible for withholding tax and National Insurance if an assignment is inside IR35.
- Requirement for Reasonable Care: Businesses cannot use blanket determinations. They must exercise reasonable care when producing an SDS; otherwise, the liability remains with them.
- HMRC Compliance Focus: HMRC focuses its enforcement efforts on helping organisations get compliance right moving forward, rather than automatically triggering retrospective reviews of prior years when a contractor transitions to an inside status.
Achieving IR35 Compliance with Certainty
For HR, procurement, and finance directors, managing an extensive contingent workforce while ensuring strict IR35 compliance can be resource-intensive. Errors in status determinations or failures in the supply chain can expose organisations to significant retrospective tax liabilities and financial penalties from HMRC.
Correct IR35 compliance requires a repeatable, robust process backed by real employment law expertise.
Partner with the IR35 experts at IR35 Shield
At IR35 Shield, we provide compliance solutions tailored for businesses, consultancies, and recruitment agencies. With over two decades of experience at the cutting edge of employment status case law, our technology and expert advisory services deliver definitive IR35 status results.
We help you demonstrate reasonable care, protect your supply chain, and secure peace of mind. Whether you need automated bulk status assessments, robust contract reviews, or complete tax investigation defence, our team is here to help your business every step of the way.
If you need help with your IR35 processes, feel free to reach out. You can email us at info@ir35shield.co.uk or get in touch with an expert to find out how we can help.
