HMRC's policy note put the expected tax revenue from the private-sector reform at £1.2 billion in 2020-21. The off-payroll working rules exist to address that scale of tax leakage by making sure people who work like employees are taxed in a similar way, even when their services are supplied through a company.
In plain English, the rules ask one practical question: if the contractor had been engaged directly, would they be an employee? If the answer is yes, the engagement is generally treated as inside IR35 for tax purposes. The result affects who makes the decision, who deducts PAYE and National Insurance, how the contractor is paid, and whether a limited company remains a sensible structure for that engagement.
This guide focuses on what happens when the rules affect real contracting decisions. You'll see how status tests work, who must issue a Status Determination Statement, what the 6 April 2026 company-size changes mean, and why an umbrella company can be a pragmatic route when a contract is assessed inside IR35.
What the off-payroll working rules are and why they exist
The off-payroll working rules, commonly known as IR35, began in 2000. Their purpose was to prevent disguised employment, where an individual works in much the same way as an employee but supplies services through an intermediary, often a personal service company. HMRC describes the underlying aim as ensuring that people doing similar work are taxed fairly, whether they work through a company or directly as employees. HMRC's contractor guidance explains the history and purpose of the off-payroll rules.
The original model placed the main status decision with the contractor's company. That changed in the public sector in 2017, when public authorities became responsible for deciding employment status and deducting PAYE and National Insurance where required. The government then announced in Autumn Budget 2018 that the reform would extend to medium and large private-sector clients. The planned start date of 6 April 2020 was later delayed because of COVID-19, and the private-sector reform began on 6 April 2021. Small businesses were excluded. The government's reform overview sets out this transition from contractor-led to client-led responsibility.
The £1.2 billion figure matters because it shows why the rules became a commercial issue for clients, not just a technical tax question. HMRC's policy note said the delayed private-sector reform was expected to raise £1.2 billion in 2020-21 under the original timetable. Read HMRC's policy note on the expected fiscal impact of the reform.
How the rules affect a normal engagement
Suppose a software specialist works through a personal service company. The client sets the specialist's hours, directs the day-to-day method of working, requires personal service, and offers continuing work with no meaningful opportunity to refuse it. The company structure alone doesn't make the engagement independent. The facts may point towards employment if the individual were contracted directly.
That's the distinction many contractors miss. IR35 doesn't ask whether you have a limited company. It asks how the engagement operates in reality. The written contract matters, but the working practices must support it. A contract describing an independent business won't protect an arrangement that functions like a staff role.
The 2021 model moved the operational burden to the client and fee-payer for medium and large private-sector organisations. That shift was designed to put the status decision with the organisation best placed to understand the work being commissioned. It also means a contractor may receive a decision that changes how payments are processed without changing the technical employment-status test itself.
The rules are therefore not designed as a trap for contractors. They're a fairness mechanism aimed at aligning tax treatment with the way work is performed. Once you understand that, the practical questions become clearer: who decides, what evidence supports the decision, and what should you do if the engagement is inside IR35?
For a contractor-focused explanation of the reforms, see what changed with the IR35 reforms and how they affect contractors.
How the employment status tests work in practice
A status assessment isn't decided by one phrase in a contract. HMRC and the courts consider the complete relationship between the worker and the client. The strongest assessment starts with the day-to-day reality, then checks whether the written terms accurately record it.
Control
Ask who decides what work is done, how it is done, when it is done, and where it is done. A client can set a project outcome without controlling the contractor's method. The risk increases when a manager directs the contractor's daily tasks, working hours, reporting line, and procedures in the same way they direct employees.
A network consultant who agrees to deliver a secure infrastructure design but chooses the technical approach has a different profile from one who follows the client's internal instructions throughout every working day. Remote work doesn't automatically establish independence, and office attendance doesn't automatically establish employment. The question is the degree of control in practice.
Substitution
A genuine right of substitution can support self-employment, but only if it's real and workable. The contractor should be able to provide a suitably skilled replacement, and the client's approval process shouldn't reduce the right to a purely theoretical clause.
For example, a specialist consultancy may agree that the company can send another qualified consultant if the named individual becomes unavailable. If the client insists that only the named person can perform the work, personal service becomes a stronger employment indicator.
Mutuality of obligation
Employees generally expect their employer to provide work and expect to accept it. Independent contractors usually agree a defined assignment and can negotiate whether to accept further work.
A client that can end a discrete project once the agreed deliverable is complete has a different relationship with a contractor from one that provides an ongoing stream of tasks and expects continuous availability. The absence of an obligation after a project doesn't decide the assessment alone, but it helps show whether the engagement is project-based or staff-like.
Financial risk and equipment
A genuine business usually carries some commercial risk. That might include correcting defective work at its own cost, dealing with unpaid invoices, pricing a project, or supplying specialist equipment. Paying for ordinary business overheads, such as accountancy, isn't enough on its own.
A contractor who quotes for a defined outcome, buys specialist tools, and may have to redo work without extra payment presents stronger business indicators than someone paid for time, using the client's equipment, with no responsibility for rectification.
Integration
Integration concerns whether the contractor becomes part of the client's organisation. A contractor who attends staff meetings, appears on the internal organisation chart, receives employee-style benefits, and follows the same management structure may look more like an employee.
That doesn't mean collaboration is prohibited. Contractors often need access to systems and must coordinate with permanent teams. The practical distinction is whether the contractor remains an independent service provider or becomes indistinguishable from the client's workforce.
Practical rule: assess what happens on an ordinary working day, not just what the contract says should happen.
These factors can point in different directions. A contractor may have specialist equipment but still work under close supervision. Another may work within a client team while controlling the method and bearing meaningful commercial risk. Use this practical guide to assess whether an engagement may sit inside or outside IR35.
Who is responsible for deciding whether the rules apply
The person making the status decision depends mainly on the client's sector and size. For public-sector clients and medium or large private-sector clients, the client determines status. The fee-payer then operates payroll deductions if the decision is inside IR35.
The client must issue a Status Determination Statement, usually called an SDS. It must state whether the off-payroll rules apply and explain the reasoning. HMRC says the client must pass the SDS to the worker and to any third party it contracts with, such as an agency. HMRC's employment-status manual explains the SDS communication requirement.
The small-company exemption
Small private-sector clients remain outside the reformed client-led rules. In that situation, the contractor's intermediary or personal service company remains responsible for making its own determination and dealing with the resulting tax treatment.
Company size is assessed using three criteria:
- Turnover: From 6 April 2026, the threshold rises from £10.2 million to £15 million.
- Balance sheet total: The threshold rises from £5.1 million to £7.5 million.
- Employee headcount: The threshold remains 50 employees.
A company is treated as small when it meets two of the three criteria. The published company-size guidance summarises the 2026 threshold changes and the two-out-of-three test.
The timing is more complicated than checking the figures on 6 April 2026. A non-group company is treated as small in its first financial year unless it meets the relevant tests for two consecutive financial years. Group-company rules and accounting periods can also affect the outcome, so contractors shouldn't assume that a client becomes exempt on the day the new thresholds take effect.
Finding the right decision-maker
Before accepting a contract, ask the agency or client:
- Is the end client a public authority?
- If it's private sector, has the client confirmed whether it's small, medium, or large?
- Who will issue the SDS?
- Who is the fee-payer?
- Which organisation will process PAYE and National Insurance if the role is inside IR35?
These questions prevent a common failure. Contractors sometimes debate their status with an agency that has no authority to make the determination, while the actual client has never completed a defensible assessment.
The 6 April 2026 threshold change may bring additional organisations into the exemption, but it can also create uncertainty during transition. A client's size, group structure, accounting periods, and previous classification may all matter. Read this guide to Status Determination Statements for a practical view of the SDS process.
Inside versus outside IR35 and the role of umbrella companies
An inside IR35 decision means the engagement is treated as employment for tax purposes. The fee-payer deducts Income Tax and employee National Insurance from the payment and accounts for employer National Insurance. HMRC's guidance confirms that the client determines status for public-sector and medium or large private-sector engagements, while the fee-payer handles the relevant payroll deductions. HMRC's explanation of off-payroll working sets out the status and PAYE responsibilities.
An outside IR35 decision means the off-payroll rules don't require the fee-payer to treat the payment as employment income under that engagement. The contractor's company can invoice for the work and manage its own accounting, subject to the normal tax rules and the actual facts of the relationship.
The practical trade-off
| Issue | Outside IR35 | Inside IR35 |
|---|---|---|
| Tax processing | The contractor's company generally manages its own tax affairs. | PAYE and employee National Insurance are deducted through the fee-payer. |
| Commercial structure | A PSC may remain appropriate where the contractor genuinely operates as an independent business. | The PSC may offer little practical advantage for that assignment because the payment receives employment-style tax treatment. |
| Administration | The contractor manages company records, invoices, accounts, and tax responsibilities. | Payroll administration is handled through the fee-payer or an umbrella arrangement. |
| Rights | Company status doesn't automatically provide employment rights. | An umbrella employment arrangement can provide statutory employment rights, depending on the employment contract. |
A contractor who receives an inside decision may still be asked to keep a PSC open, particularly where the supply chain is already established. That can create an unattractive combination of company administration and employment-style taxation. The deemed employment payment also interacts with Corporation Tax, dividend, and CIS calculations, so errors can extend beyond a single payslip. HMRC's policy material explains how the deemed employment payment feeds into wider company calculations.
Why an umbrella company is often the pragmatic fallback
An umbrella company employs the contractor and processes pay through PAYE. The agency or client pays the umbrella's assignment rate, and the umbrella accounts for deductions before paying the contractor's wages. The contractor receives a payslip showing the relevant deductions and usually receives statutory employment rights under the umbrella employment contract.
That arrangement doesn't make an inside contract more profitable. It does make the employment and payroll position clearer, and it avoids forcing a PSC to remain at the centre of an engagement that is already being taxed as employment.
Contractors should compare the assignment rate with the expected gross pay, employer costs, pension treatment, holiday pay, and umbrella margin. Accreditation or assessment by bodies such as FCSA or Professional Passport can be useful due-diligence signals, although contractors should still read the employment contract and payslip carefully.
Learn how umbrella companies work and what to check before joining one. Umbrella Company offers a comparison service for contractors considering providers for inside and outside IR35 engagements, with comparisons shaped around factors such as role and pay arrangements.
Compliance steps and a contractor readiness checklist
The first document to request is the Status Determination Statement. Don't rely on a verbal comment from a recruiter or a short email saying that a role is inside IR35. The SDS should state the decision and give the reasons, and the client must pass it to you and any relevant agency or other contracted intermediary.
Read the reasoning against the actual working arrangement. If the SDS says you control your work but the project manager will dictate your daily method, that inconsistency deserves attention. If the client dismisses a substitution clause because the work requires a named specialist, ask whether the contract and working practices support substitution.
A practical response when the decision looks wrong
Start with facts, not frustration. Identify the specific part of the reasoning you dispute, then provide evidence such as the scope of work, deliverables, substitution terms, equipment arrangements, correction obligations, and communications about control.
The client must have a process for responding to disagreements. Keep your challenge focused and professional, and retain the original SDS, your response, the client's reply, the contract, and records of how the work is performed.
A good audit trail should allow someone outside the engagement to understand why the decision was made and whether the working practices matched it. Contractors who need a broader record-keeping framework may find this LMS audit trail compliance guide useful when organising evidence and review histories.
You should also confirm who will operate payroll. If the contract is inside IR35, the fee-payer must account for PAYE and National Insurance in line with the determination. If the supply chain can't explain who holds that responsibility, resolve the uncertainty before work begins.
Contractor readiness checklist
- Request the SDS: Obtain the written decision and its reasoning before relying on the proposed payment route.
- Test the reasoning: Compare the SDS with control, substitution, mutuality of obligation, financial risk, equipment, and integration.
- Confirm the fee-payer: Ask which organisation will process PAYE and National Insurance if the engagement is inside IR35.
- Review the structure: Decide whether your PSC remains suitable or whether an umbrella employment arrangement is more practical.
- Keep evidence: Save the contract, SDS, challenge correspondence, working instructions, invoices, and relevant project records.
- Track reviews: Ask how and when the client reviews status, especially if duties, management, location, or deliverables change.
A revised determination isn't just an informal update. HMRC says the organisation should prepare a new SDS, explain the revised decision, and state the date from which it takes effect. Read HMRC's guidance on updating status determinations.
The effective approach is continuous governance. The weak approach is to obtain an SDS at the start, file it away, and ignore a change in working practices.
The video below offers another practical format for reviewing contractor readiness.
Sector-specific realities and what contractors should watch for
The legal tests apply across sectors, but the facts carrying most weight differ. A software developer, finance consultant, construction professional, and healthcare specialist may all work through companies while showing very different working relationships.
IT and technology
Project-based technology work may support an outside-IR35 position where the contractor controls the method, delivers defined outcomes, and retains a genuine right to provide suitably skilled assistance. The position becomes harder where the contractor joins a permanent development squad, attends the client's ceremonies, follows its management hierarchy, and receives daily task instructions.
Remote work does not decide status. A remote contractor can remain under extensive control, while an independent consultant can work at the client's premises without becoming integrated. Examine who controls the work, how performance is managed, and whether the engagement provides a defined service or additional capacity.
Finance and professional services
Finance contractors often handle confidential systems, regulated processes, and client-specific reporting lines. Those requirements may be commercially necessary without creating employment. The assessment should separate access and collaboration from managerial control.
Financial risk also matters. A consultant who prices and accepts responsibility for a defined piece of work presents a different picture from someone paid only for time, with no obligation to correct errors or deliver a particular outcome.
Construction and CIS
Construction causes particular confusion because the Construction Industry Scheme and IR35 are separate systems. CIS deductions can apply to construction payments, while IR35 asks whether an individual working through an intermediary would be an employee if engaged directly. One system does not replace the other.
A site-based worker who follows a site manager's daily instructions, must attend personally, and uses client-provided equipment may show stronger employment indicators. A contractor taking defined projects, controlling the method, supplying tools, and accepting genuine responsibility for rectification may show a different pattern. The contract must match the work as performed, not merely describe an intended arrangement.
Healthcare
Healthcare engagements often involve personal qualifications, patient-safety requirements, rotas, and agency involvement. Personal clinical service may be unavoidable, but the wider relationship still determines the picture. Check who controls the rota, who supplies the setting and equipment, whether the worker can decline assignments, and how the service is managed.
Sector-specific evidence is more useful than generic IR35 wording. Keep project scopes, deliverables, instructions, change records, substitution discussions, and evidence of correction or commercial risk where they reflect the actual engagement.
The tax exposure explains why large clients treat status determinations seriously, as noted in the HMRC policy analysis above. For contractors, the practical issue is the effect of that determination on pay and the available working structure. If an engagement is inside IR35, an umbrella arrangement may be the most workable fallback because PAYE processing is built into the supply chain, although assignment rates, deductions, and provider standards still need checking.
A comparison service such as Umbrella Company can help contractors review providers before accepting an inside engagement. The choice is a trade-off between administrative simplicity and the commercial terms of employment, not a way to change the underlying status decision.
Frequently asked questions about off-payroll working
Does one determination cover every contract with the same client?
Not necessarily. Status depends on the specific engagement and its actual working practices. A client may assess two contracts differently if the deliverables, control, substitution rights, management arrangements, or commercial risk differ.
Ask for the SDS for the engagement you're accepting, rather than assuming an earlier decision automatically applies.
What happens to an existing contract after the April 2026 threshold change?
The client's classification may not change immediately when the new thresholds begin. The relevant accounting periods and the requirement for a non-group company to meet the size tests for two consecutive financial years can affect when the exemption applies. Contractors should ask the client or agency for its classification, the effective date, and whether group-company rules have been considered.
What should I do if the client doesn't issue an SDS?
Ask the client and agency in writing for the statement and the reasoning. Don't assume that silence means the contract is outside IR35. Until the supply chain confirms who is responsible for the determination and payroll treatment, get professional advice before choosing how to invoice or draw money through your company.
Do umbrella company margins and standards vary?
Yes, commercial terms and service quality can vary. Compare the assignment rate, expected gross pay, deductions, employment contract, pension arrangements, holiday-pay treatment, and the umbrella margin. FCSA and Professional Passport membership can support due diligence, but read the provider's documents and check that your payslip matches the promised process.
Use the Umbrella Company comparison service to evaluate providers that support contractors working on both inside and outside IR35 engagements.
Umbrella Company helps contractors and freelancers compare umbrella providers based on their role, pay arrangements, and IR35 requirements. Visit Umbrella Company to compare suitable options before your next engagement and make the payroll decision with clearer information.
