IR35 And PSCs: What UK Businesses Need To Know

If you engage independent contractors through their personal service companies (PSCs), IR35 can feel like a maze of acronyms, tax rules and risk. As a small business, you don’t want surprises - you want to know when the off‑payroll working rules apply, how to assess a contractor’s status, and what to put in your contracts and processes so you’re protected from day one.

In this guide, we break down IR35 from the client/hirer’s perspective in clear, practical steps. You’ll learn when the rules bite, how to make a defensible Status Determination Statement (SDS), what to watch in your agreements and working practices, and what to do if an engagement is “inside IR35”.

What Is IR35 And Why It Matters For Small Businesses Working With PSCs?

IR35 is a set of UK tax rules designed to tackle “disguised employment.” In simple terms, HMRC looks past the PSC and asks: if we ignore the company, is the individual effectively working like your employee? If yes, income tax and National Insurance Contributions (NICs) may need to be deducted at source - much like for an employee.

Two frameworks matter in practice:

• Intermediaries legislation (often called “IR35”) within ITEPA 2003 - the overall test of whether an engagement looks like employment;
• Off‑payroll working rules (Chapter 10 ITEPA) - who in the supply chain is responsible for doing the employment status assessment and operating PAYE/NICs.

Since April 2021, medium and large private‑sector clients must assess status and issue an SDS. Small private‑sector clients are generally exempt (the PSC handles IR35 itself). Understanding which side of the line you fall on is step one.

Employment status is judged on the real terms of the engagement. The key questions mirror the common employment status tests used across UK law: who controls how, when and where work is done; is there a genuine right of substitution; and is there “mutuality of obligation” (an ongoing obligation to offer and accept work). If, looking at the whole picture, the engagement is more like employment, it’s likely inside IR35.

This distinction sits alongside the familiar categories in UK employment law. If you’re grappling with the boundaries between categories, our explainer on worker vs employee is a useful backdrop when you’re thinking about day‑to‑day rights and obligations separate from tax.

Do The Off‑Payroll Rules Apply To You? (Small Company Test And Scope)

Before you do a status assessment, confirm whether the off‑payroll working rules actually apply to your business for the tax year.

Small Company Exemption (Private Sector)

You’re exempt if you’re “small” for Companies Act purposes. In broad terms, you’re small if you meet at least two of these thresholds (for the financial year):

• Annual turnover not more than £10.2 million;
• Balance sheet total not more than £5.1 million;
• Average number of employees not more than 50.

Unincorporated clients have a turnover‑based test (broadly, turnover not more than £10.2 million). If you’re small, the PSC remains responsible for IR35 and you don’t have to issue an SDS. However, it’s still wise to sanity‑check status - you’ll be shaping the terms and working practices, so your choices can influence the contractor’s own tax risk and your commercial relationship.

Medium/Large Clients (Private Sector) And Public Sector

If you’re not small, you must decide the contractor’s status for each assignment and issue an SDS to the individual and the next party in the chain (for example, an agency). You must take “reasonable care” in doing so. If you don’t, liability for PAYE/NICs can transfer to you, even if there’s an agency or fee‑payer in the middle.

Who’s In Scope?

These rules apply to engagements where an individual personally provides services to you via an intermediary (typically a PSC). They don’t apply to engagements through genuinely outsourced deliverables (for example, a supplier undertaking a discrete project with its own staff and supervision) - but labels aren’t enough. HMRC will test the reality of the arrangement.

Making A Status Determination: Practical Steps And Evidence

A robust status process reduces the chance of HMRC challenge and keeps your supply chain aligned. Here’s a practical way to handle it.

1) Identify Roles That Use PSC Contractors

Map the roles you typically fill via contractors and note where a PSC intermediary is involved. Consider whether a different model - for example, hiring fixed‑term employees or using a managed service provider - would reduce risk for certain roles.

2) Gather Facts About The Working Practices

Status is about what actually happens day to day. Speak with the team that will manage the contractor and the contractor/agency. Document facts such as:

• Substitution: is there a genuine, unfettered right of substitution, and has it been used in practice?
• Control: who decides how, when and where the work is done? Are there set hours or rotas?
• Mutuality of obligation: can you decline work and can the contractor refuse tasks without penalty?
• Financial risk: does the PSC fix defects at its own cost? Is there scope‑based pricing?
• Equipment: whose tools, kit and software accounts are used?
• Integration: is the individual held out like a member of staff (e.g. internal directories, management duties)?

3) Use a Tool - But Don’t Rely On It Blindly

HMRC’s CEST tool can be a starting point, but it only provides a reliable outcome if the inputs reflect reality. Treat it as one piece of evidence, not the whole assessment. If CEST returns “unable to determine,” escalate for a more detailed review.

4) Draft And Issue An SDS (With Reasons)

Record your conclusion - inside or outside IR35 - with reasons. Provide the SDS to the contractor and the next party in the chain before work starts or as soon as possible. Keep evidence of how you took reasonable care (for example, questionnaires, emails, meeting notes, tool outputs).

5) Operate A Client‑Led Disagreement Process

If the individual or fee‑payer disagrees, you have 45 days to respond. Re‑review the facts, consider additional evidence and either amend the SDS or confirm the original decision with reasons. Keep a clear audit trail.

If this feels like a lot of admin, you’re not alone. The good news is that once you set up a repeatable process and align your documents and practices, it becomes a manageable BAU task.

Contracting With PSCs: Clauses And Structures That Support Your Decision

Contracts won’t override reality - but they do matter. A well‑structured agreement that reflects genuine independence will support an outside‑IR35 conclusion. Conversely, if you’ve decided an engagement is inside IR35, your contract should be clear about rates, tax deductions and control.

Key Clauses For Outside‑IR35 Engagements

• Substitution: a genuine, practical right for the PSC to provide a suitably qualified substitute, with a clear approval process focused on capability and security rather than unfettered veto.
• Control: outcomes‑focused specification, minimal day‑to‑day direction by you, flexibility on how and where work is done (subject to security and health and safety).
• Deliverables And Milestones: project‑based scope with acceptance criteria and the possibility of re‑performance at the PSC’s cost if deliverables don’t meet spec.
• Financial Risk: provisions that show business‑to‑business risk, such as rectification obligations, capped rework, and professional indemnity insurance.
• Equipment: the PSC provides its own tools where feasible; where you must provide systems access, limit this to what’s necessary for security/integration.

It’s essential to use a tailored Contractors Agreement or consultancy contract rather than a generic template. Clear business‑to‑business language and well‑drafted deliverables make it easier to uphold the status decision.

Agency Chains And Statements Of Work

If you hire through an agency, ensure the entire chain reflects the intended status. Consistent terms across your contract with the agency and any Statement of Work are key. If you rely on agencies often, having a strong grasp of agency relationships helps control IR35 risks and fee‑payer obligations.

Inside‑IR35 Set‑Up

Where the facts point to employment‑like working, don’t force “outside” language. For inside‑IR35 engagements (for medium/large clients), build in:

• Clear rate cards that reflect the cost of operating PAYE/NICs at the fee‑payer level;
• On‑site control, hours, and supervision clauses consistent with the reality;
• Express confirmation that the fee‑payer will operate PAYE/NICs on the deemed direct payment.

Remember: restrictive covenants can apply in B2B contracts too. If you need post‑engagement protections, use proportionate restrictions drafted for a contractor context - see our guidance on non‑compete clauses for what’s reasonable.

Paying And Reporting When Inside IR35 (Payroll, VAT And Agencies)

If you’re medium/large and your SDS says “inside IR35,” the fee‑payer (often the agency; otherwise, you) must treat payments to the PSC as if they are to an employee for tax purposes.

Who Operates PAYE/NICs?

• If there’s an agency in the chain and it pays the PSC, the agency is the fee‑payer and must deduct PAYE/NICs and pay Employer NICs (and apprenticeship levy if applicable).
• If you pay the PSC directly (no agency), you are the fee‑payer and must run payroll on the deemed direct payment.

What Is The “Deemed Direct Payment”?

It’s broadly the amount you pay the PSC for the work, minus VAT and allowable direct costs like certain expenses already subject to tax/NICs elsewhere. The fee‑payer calculates income tax and employee NICs on that deemed amount, pays those to HMRC, and pays net to the PSC. Employer NICs and any apprenticeship levy are additional costs for the fee‑payer.

Do You Still Pay VAT?

Yes. If the PSC is VAT‑registered, VAT is still charged on the invoice for the supply. The payroll calculation is done on the amount excluding VAT. Keep your invoicing and payroll processes aligned so you don’t accidentally calculate PAYE on the VAT element.

Pensions, Benefits And Employment Rights

Operating PAYE for tax purposes does not, by itself, make the contractor your employee for employment law rights. But because the engagement looks employment‑like, you should be careful about onboarding processes, benefits and workplace policies to avoid blurring lines unnecessarily. If you’re unsure where the boundaries lie in practice, revisit the employment status tests and ensure your internal practices match the tax treatment.

IR35 Risk Management Checklist For Small Businesses

Here are practical controls to reduce IR35 headaches and keep your supply chain compliant.

1) Decide The Right Resourcing Model

Not every role suits a PSC engagement. For ongoing, supervised roles, a fixed‑term employment route might be cleaner. For deliverables‑based projects, a consultancy model with a robust scope and acceptance criteria can genuinely sit outside IR35. If you engage overseas talent, remember that UK tax rules can still apply where the work is performed for a UK client and the duties are carried out in the UK - and there are extra procurement and data issues when engaging overseas contractors.

2) Build A Repeatable Status Process

• Pre‑engagement questionnaire focused on substitution, control, MOO, financial risk and equipment.
• Documented SDS with reasons and a clear disagreement process (45‑day response).
• Annual re‑assessment for long engagements or when working practices change.

3) Align Contracts With Reality

Use a tailored Contractors Agreement or project‑based SOW. Make sure everything in the paper matches how the work will actually run. If an agency sits between you and the PSC, the agency contract should mirror your SDS conclusions and place fee‑payer responsibilities where they belong.

4) Keep “Working Practices” Clean

• Avoid setting fixed hours or rotas for outside‑IR35 roles; focus on outcomes and deadlines.
• Enable practical substitution (and don’t block it without good reason related to capability or security).
• Limit staff‑like integration: steer away from line‑management responsibilities, staff benefits and company‑wide obligations unless truly necessary for safety or compliance.

5) Plan Your Supply Chain Liability

Where there’s an agency chain, understand who is the fee‑payer. HMRC can transfer debt up the chain if obligations aren’t met. Consider appropriate indemnities and audit rights in your agreements and make sure your agency partners have the systems to operate off‑payroll correctly. If you use layered subcontracting, be clear on who is doing what - our note on contractor vs subcontractor helps clarify responsibilities down the line.

6) Train Your Managers

Most IR35 issues arise from well‑meaning managers treating contractors like staff. Short, practical training on what “outside‑IR35” looks like in daily life (substitution, autonomy, deliverables) can save you from creeping status drift.

7) Review When Anything Material Changes

Change of role, location, management, scope, or length of engagement? Re‑check the SDS. If contractors start covering staff duties (for example, supervising teams, attending appraisals, or taking on rota‑based obligations), your status may shift.

8) Use Clear, Commercial Clauses

Beyond IR35, robust commercial terms make relationships smoother: notice periods that work for project‑based resourcing, fair IP clauses, confidentiality, and post‑project restrictions that are reasonable for a contractor context. If you’re building a panel of specialists, consider a framework with call‑off statements and consistent terms so you’re not renegotiating the basics each time.

Key Takeaways

• Start with scope: confirm whether the off‑payroll rules apply to you this year. If you’re “small,” the PSC handles IR35; otherwise, you must assess and issue an SDS.
• Status is about reality. Substitution, control and mutuality of obligation are the big three - but HMRC will weigh the whole picture, including financial risk and integration.
• Take reasonable care: gather facts, use tools sensibly, record your reasoning, and respond to disagreements within 45 days. Good process is your best defence.
• Contracts matter when they reflect reality. Use a tailored Contractors Agreement or consultancy terms that support an outside‑IR35 decision, or set clear payroll expectations for inside‑IR35 roles.
• If an engagement is inside IR35, the fee‑payer operates PAYE/NICs on the deemed direct payment and pays VAT separately. Get your invoicing and payroll aligned to avoid errors.
• Train managers and monitor working practices. Most IR35 problems come from staff‑like treatment that drifts away from what the contract says.
• Where agencies are involved, align the whole chain. Understand who is fee‑payer, build audit rights and use consistent, practical clauses across your supply chain.

Getting your IR35 approach right can feel daunting at first, but once you put the core building blocks in place - a clear process, consistent contracts and manager training - it becomes a manageable part of how you resource projects. If you’d like a second pair of eyes on your process or you want us to draft contractor‑friendly consultancy terms that support your status decisions, we’re here to help.

If you’d like help with IR35 or working with PSCs, you can reach us at 08081347754 or team@sprintlaw.co.uk for a free, no‑obligations chat.