IR35 Risk: What UK SMEs Need To Know When Hiring Contractors

Hiring contractors can be a smart way to scale your business quickly, bring in specialist skills, and keep your fixed payroll costs under control.

But if you’re a UK SME, there’s one issue you don’t want to ignore: IR35 risk.

IR35 (also called the “off-payroll working rules”) is essentially about one question: is the person you’re calling a contractor actually working like an employee? If the reality of the working relationship looks like employment, HMRC may expect broadly similar tax and National Insurance outcomes to employment - even if invoices are being raised through a limited company.

The good news is you can take steps to manage IR35 risk. The key is to understand what drives it, build the right processes, and put the right documents in place from day one.

What Is IR35 Risk (And Why Does It Catch SMEs Out)?

IR35 risk is the risk that a contractor engagement is treated as “disguised employment” for tax purposes.

This usually comes up where:

• you engage an individual through their personal service company (PSC) (often a limited company); and
• the day-to-day working setup looks and feels like employment.

When businesses talk about “being caught by IR35”, they typically mean that HMRC views the contractor as effectively an employee, and this can lead to:

• unexpected tax/NIC liabilities (potentially going back years, depending on the circumstances);
• interest and possible penalties;
• management time spent dealing with HMRC; and
• commercial disruption (including contractors leaving if the arrangement changes).

IR35 risk often catches SMEs out because contractor hiring can grow organically. You start with “we just need a developer for a few months” or “we need a marketing specialist two days a week” - and before you know it, they’re embedded in your business like a team member.

It’s also worth noting that IR35 isn’t just a “big business” problem. SMEs can still face real exposure if the facts point towards employment. (This article is a general legal overview only and isn’t tax advice - IR35 status and any liabilities depend on the specific facts and HMRC guidance, so you may wish to speak to an accountant or tax adviser.)

Why IR35 Risk Matters When You’re Hiring Contractors

From a small business perspective, IR35 risk is less about legal theory and more about business impact.

Here’s why it matters:

1) It Can Create Unexpected Cost

If a contractor is found to be “inside IR35” (in broad terms), the total tax/NIC position can be very different from what you expected when you agreed the day rate.

Even if you did everything in good faith, the practical outcome can be: you pay more than budgeted, or you end up renegotiating rates, or both.

2) It’s A Compliance And Governance Issue

Many SMEs choose to run checks on contractor status - especially where contractors are a core part of delivery. If you’re raising investment, going through due diligence, or working with larger clients, you might be asked to explain how you approach contractor status and manage IR35 risk.

3) It Can Affect Your Contractor Relationships

Contractors often care a lot about status decisions and working practices. If you change the way you work with them (for example, tighter supervision, fixed hours, or restricting substitution), you might unintentionally increase IR35 risk - or you might push a contractor into an arrangement they’re not comfortable with.

4) The “Label” Doesn’t Decide It

This is where SMEs can get caught out. Calling someone a “contractor” and having them invoice you doesn’t automatically make it a contractor relationship.

The day-to-day reality matters. That’s why it’s important to get the fundamentals right, including how you structure the engagement and what you put in writing. If you’re relying on a template, or if the agreement doesn’t match how you actually work together, you’re taking on avoidable IR35 risk.

As a starting point, it helps to understand the difference between employment and contracting principles (including control, personal service and mutuality of obligation). The same issues also come up outside IR35, for example when looking at employment status generally - see Employment Status.

Common IR35 Risk Triggers (What HMRC Will Look At In Practice)

When you’re assessing IR35 risk, it helps to think in plain English: does this person operate an independent business, or are they effectively part of your team?

While every situation depends on its facts, these are some of the most common risk triggers:

Control: Do You Control How They Work?

Control is a big one. If you tell a contractor:

• what to do;
• how to do it;
• when to do it; and
• where to do it (beyond what’s genuinely necessary),

it starts to look like employment.

Some control is normal - you’re paying for an outcome. But if the contractor is being managed like an employee (daily stand-ups, task-by-task direction, performance management style oversight), IR35 risk increases.

Personal Service: Can They Send A Substitute?

Independent contractors typically have the ability (at least in principle) to provide a substitute. If your arrangement requires a specific individual to do the work personally, and substitution isn’t realistically possible, that can increase IR35 risk.

This doesn’t mean every contractor must regularly send substitutes. But a genuine right of substitution (and a workable process for it) can be an important indicator of a contractor relationship.

Mutuality Of Obligation (MOO): Are You Obliged To Offer Work, And Are They Obliged To Accept It?

MOO is one of the most misunderstood areas.

In practical terms, higher risk situations include:

• you’re expected to keep providing work continuously; and
• the contractor is expected to keep accepting it, much like an employee would.

Project-based engagements with clear end points generally sit more comfortably in contractor territory than open-ended “rolling” arrangements.

Integration: Do They Look Like Part Of Your Business?

If the contractor:

• manages employees;
• represents you externally as part of the team;
• has a company email address indistinguishable from staff;
• appears on your org chart; or
• is subject to staff policies in the same way as employees,

that can increase IR35 risk.

It’s not that contractors can’t work closely with you - they often do - but you want to avoid “blurring” the relationship so much that it becomes hard to distinguish from employment.

Financial Risk And “Being In Business On Their Own Account”

Contractors are generally expected to take on some financial risk and operate like a business. Signs of this can include:

• they provide their own equipment (where appropriate);
• they have multiple clients;
• they can make a profit (and face losses) based on how they run their work; and
• they fix defective work at their own cost (where that makes sense for the service).

If, by contrast, the contractor is paid like an employee (fixed daily pay, no meaningful financial risk, no responsibility to fix issues, reimbursed like staff), IR35 risk can creep up.

How To Reduce IR35 Risk: A Practical Step-By-Step For SMEs

Managing IR35 risk doesn’t have to be overwhelming. The goal is to build a repeatable process you can use every time you hire a contractor.

Step 1: Be Clear On What You’re Actually Hiring

Start by defining the engagement properly:

• Is it a project with deliverables and an end date?
• Or is it “extra hands” to support ongoing operations?
• Do you need a specific person, or just a capability?

If what you really need is someone to work set hours under close direction, that may be an employment hire (or worker engagement) rather than contracting - and treating it as contracting can increase IR35 risk.

If you’re unsure, it’s often worth sanity-checking the setup early, before the working arrangement becomes embedded. (For tax-specific guidance on IR35, you should speak to an accountant or tax adviser.)

Step 2: Structure The Work Like A Contractor Engagement (Not A Job)

A practical tip: design the “shape” of the engagement to match a business-to-business service.

For example:

• Scope: define deliverables, milestones, or outputs (rather than a list of ongoing duties).
• Timescales: use a fixed term or project end point, with extensions agreed separately.
• Autonomy: allow the contractor to decide how the work is done (within reasonable parameters).
• Substitution: if appropriate, build a workable substitution process.

This is also where the written terms matter. A properly drafted Contractor Agreement can help document the intended relationship and set boundaries that reduce confusion later.

Step 3: Align Day-To-Day Working Practices With The Paperwork

One of the biggest IR35 risk traps is the mismatch between:

• what your contract says; and
• what your team does day-to-day.

For example, your agreement might say “the contractor controls their working hours”, but in practice your manager expects them online 9–5 every day and approves leave like an employee.

HMRC will care far more about what actually happens than what the contract says.

A simple way to manage this is to do a short internal checklist for each contractor:

• Who assigns work and how?
• Are deliverables used, or are tasks managed like an employee workload?
• Do they attend staff meetings? If yes, which ones and why?
• Do they have authority over employees?
• Can they work off-site where practical?

Step 4: Avoid Accidentally Creating Employment-Like Entitlements

Be careful about offering contractor “perks” that look like employment, such as:

• paid holiday (rather than unpaid time off, or being unavailable between milestones);
• sick pay arrangements that mirror employees;
• employee benefits (gym memberships, private healthcare, etc.); and
• staff-only bonuses or incentives.

This doesn’t mean you can’t treat contractors well (you should). It just means your approach should stay consistent with a supplier relationship.

Step 5: Get The Legal Documents Right From Day One

When you’re moving quickly, it’s tempting to start work on a handshake and “sort the paperwork later”. That’s where problems start - not only for IR35 risk, but also around IP ownership, confidentiality, liability, and payment disputes.

At a minimum, you’ll want a signed agreement before work starts. If you’re currently engaging people without clear written terms, this can also create wider risks beyond IR35 - see Written Contract.

Depending on the engagement, you might use a Consulting Agreement or a contractor-specific document, but the key is that it reflects reality and protects your business.

What To Include In Your Contractor Setup To Manage IR35 Risk

Managing IR35 risk is partly about legal structure and partly about good operational hygiene. Here are the key areas SMEs should think about when hiring contractors.

A Clear Contractor Agreement (Tailored To Your Business)

A strong contractor agreement should usually cover:

• Scope of services: clear deliverables and project framing.
• Status wording: confirming the intention is an independent contractor relationship (while recognising that reality matters too).
• Substitution: where appropriate, a genuine right of substitution with a sensible approval process.
• Control: avoiding clauses that give you employee-like control, while keeping necessary oversight for quality and security.
• Fees and invoicing: what triggers payment, when invoices are issued, and payment timeframes.
• Confidentiality: protection of your sensitive information and client data.
• IP ownership: ensuring your business owns what it pays for (a major issue in tech/creative work).
• Liability: sensible limitations and risk allocation (tailored to the engagement).
• Termination: how either party can end the arrangement and what happens to work in progress.

If you’re also working through broader commercial terms (for example, a master services agreement plus statements of work), it helps to make sure the overall structure fits basic contract principles. A quick refresher on Contract Law can help you sense-check how your documents fit together.

Practical Boundaries Around Management And Performance

SMEs often bring contractors in because you need speed and accountability - totally fair. Just be mindful of how accountability is applied.

Try to:

• measure performance against deliverables and deadlines (not “time spent online”);
• avoid running a contractor through employee-style disciplinary or performance processes; and
• route contractor instructions through a single point of contact to keep the engagement consistent.

Policies That Protect Your Business Without Turning Contractors Into Staff

It’s normal to require contractors to follow certain rules, especially around confidentiality, security, and acceptable use of your systems.

Just be careful not to automatically apply the entire staff handbook as if they’re employees. Instead, you can reference specific policies that are genuinely required for risk management.

For example, if contractors use your IT systems, it can be sensible to require compliance with an Acceptable Use Policy (focused on security and data protection rather than employment-type conduct rules).

Keep Records (So You Can Prove Your Thinking)

If your contractor model is important to your business, a lightweight record-keeping approach can really help. For example:

• a short status assessment note when you engage a contractor;
• the signed contract and any statements of work;
• invoices and payment records; and
• any agreed changes to scope or extensions.

This is the kind of practical governance that helps you manage IR35 risk as you scale, especially if your contractor numbers grow over time.

Key Takeaways

• IR35 risk is the risk that a contractor engagement is treated as disguised employment for tax purposes, based on the reality of the working relationship.
• For SMEs, IR35 risk isn’t just a “tax technicality” - it can create real costs and disruption, and may also come up in due diligence as your business grows.
• High-risk contractor setups often involve employee-like control, no genuine substitution, ongoing mutual obligations, and contractors becoming integrated into your team.
• You can reduce IR35 risk by structuring work around deliverables, keeping contractor autonomy where possible, and making sure day-to-day practices match your paperwork.
• A tailored contractor agreement (plus sensible supporting policies) helps you set boundaries, protect IP and confidentiality, and avoid misunderstandings from day one.
• If you’re unsure whether an engagement looks more like contracting or employment, it’s worth getting advice early - fixing it later is usually harder and more expensive. (For tax advice on IR35 specifically, speak to an accountant or tax adviser.)

If you would like help with contractor documents and structuring contractor engagements, you can reach us at 08081347754 or team@sprintlaw.co.uk for a free, no-obligations chat.