IR35 Contract Checklist 2026: 14 Clauses That Protect Freelancers

How IR35 Status Is Actually Determined

IR35 exists to catch "disguised employment" — where someone is effectively working as an employee but operating through a limited company (or, increasingly, as a sole trader) to pay less tax.

HMRC looks at three main factors when assessing IR35 status:

1. Substitution — Can you send someone else to do the work?
2. Control — Does the client dictate how, when, and where you work?
3. Mutuality of obligation — Are you expected to accept all work offered? Does the client have to offer it?

If all three point strongly towards employment, you are likely inside IR35. If they clearly point towards genuine self-employment, you are outside.

Your contract is evidence of the intended relationship. If it contradicts the actual working arrangements, the actual arrangements win. Both must point in the same direction.

1. Right of Substitution

This is the most powerful IR35 indicator — and the most frequently missing from contractor agreements.

What it should say: You have the right to provide a suitably qualified substitute to perform the services, subject to the client's reasonable approval. The client cannot unreasonably withhold that approval.

Why it matters: A genuine business can send a substitute. An employee cannot. HMRC's position is that if a company hired "you specifically", that is employment — not a business-to-business arrangement.

Common mistake: Having a substitution clause that is so restricted (e.g. requires client's absolute discretion to refuse) that it is meaningless. HMRC will discount such clauses.

Checklist:

• ✅ Right to substitute is stated explicitly
• ✅ Approval cannot be unreasonably withheld
• ✅ You are responsible for paying the substitute
• ✅ You remain responsible for the quality of work delivered

2. Control Clauses

Control is about how the work is done — not just what the output is.

What it should say: The contractor determines the method by which the services are performed. The client specifies the desired outcome, not the process.

Why it matters: If the client tells you exactly how to do every task, supervises your day-to-day work, and can redirect your efforts at any time — that is control. Control = employment indicator.

Checklist:

• ✅ You determine the method of work, not the client
• ✅ Client specifies deliverables, not processes
• ✅ No clause giving client right to redirect your work at will
• ✅ No requirement to attend daily standups or management meetings as if an employee

3. Mutuality of Obligation

Mutuality of obligation (MOO) means the client is obliged to offer work, and you are obliged to accept it. That is an employment relationship.

What it should say: The client is under no obligation to offer further work, and the contractor is under no obligation to accept further work, beyond the specific project or statement of work being contracted.

Checklist:

• ✅ Contract is for a specific project or defined period — not open-ended
• ✅ No obligation on the client to offer further engagements
• ✅ No obligation on you to accept further work if offered
• ✅ Rolling contract renewals are explicitly at both parties' discretion

4. Deliverables-Based Scope

A service-based contract focuses on what you will deliver. An employment contract focuses on your time.

What it should say: Clearly define the deliverables, outputs, or project outcomes — not just hours per day or a vague "provide services as required".

Checklist:

• ✅ Statement of Work defines specific outputs
• ✅ Payment is linked to deliverables or milestones, not time attendance
• ✅ You are responsible for rectifying defective work at your own cost (financial risk)

5. Equipment and Tools

What it should say: The contractor provides their own equipment, software, and tools to perform the services. The client does not supply equipment (or if they must for security reasons, this is explicitly for security/access reasons only).

Checklist:

• ✅ You use your own laptop, software, and tools
• ✅ If client equipment is required, the contract explains why (security / system access)
• ✅ Client does not pay for your phone, broadband, or software subscriptions

6. Financial Risk

Genuine businesses carry financial risk. Employees do not.

What it should say: The contractor bears financial risk — including liability for correcting defective work at their own cost, professional indemnity insurance obligations, and no guarantee of a minimum income.

Checklist:

• ✅ You carry professional indemnity insurance (and the contract references it)
• ✅ You are liable to rectify defective work without additional payment
• ✅ No sick pay or holiday pay provision
• ✅ No minimum hours guarantee

7. No Exclusivity

What it should say: The contractor is free to perform services for other clients during the engagement. There is no restriction on working with third parties (except where it would create a direct conflict of interest).

Checklist:

• ✅ No exclusivity clause
• ✅ Any non-compete clause is time-limited and reasonable — not a broad ban on working in your sector
• ✅ You are actively working with other clients (HMRC may ask)

8. Integration / Part of the Organisation

The more integrated into the client's business you appear, the more HMRC sees employment.

What to avoid in the contract:

• ❌ Being given a company email address as your primary contact
• ❌ Being listed in the client's staff directory
• ❌ Having a company ID card like employees
• ❌ Attending company all-hands or team social events as a "team member"

These are not always avoidable (some clients require site access), but the contract should not imply integration where it is not necessary.

9. Termination Clauses

What it should say: Either party may terminate on reasonable notice. No employment-style protections (notice periods that mirror employee rights, redundancy provisions).

Checklist:

• ✅ Termination notice is reasonable for a business contract (typically 1–4 weeks)
• ✅ No provisions for "wrongful termination" similar to employment law
• ✅ Immediate termination is possible for material breach

10. Working Hours and Location

What it should say: You determine your own working hours and location, subject to availability for agreed meetings or deadlines.

Checklist:

• ✅ No prescribed start and finish times
• ✅ No requirement to be present on-site five days a week unless genuinely required by the work
• ✅ You can work from your own premises where the work allows

11. Payment Structure

What it should say: Payment is made against invoices raised by the contractor. The client does not operate PAYE. Payment terms are business-to-business (e.g. 30 days from invoice).

Checklist:

• ✅ You raise invoices — the client does not generate payslips
• ✅ No salary-style monthly payment on a specific date
• ✅ VAT is charged if you are VAT-registered
• ✅ Invoice numbers, your business name, and business address appear on invoices

12. Business Name and Invoicing

You are contracting as a business, not as an individual. The contract should reflect that.

Checklist:

• ✅ Contract is between two business entities (your company or trading name and the client)
• ✅ Your business address is on the contract
• ✅ You invoice under your business name with a business bank account

13. Dispute Resolution

While less directly relevant to IR35 status, a professional dispute resolution clause reinforces the business-to-business nature of the relationship.

What it should say: Disputes are resolved through commercial dispute mechanisms — negotiation, mediation, then arbitration or litigation. Not employment tribunal procedures.

14. Status Determination Statement (SDS)

For medium and large private sector clients, you are entitled to a Status Determination Statement under the off-payroll working rules. This is HMRC's formal assessment of your IR35 status for this specific engagement.

What to do:

• Ask the client (or their agency) for the SDS before you start work
• If they assess you as inside IR35 and you disagree, you can challenge it through the client's disagreement process
• Keep a copy — it is your protection if HMRC investigates later

If the client is small (turnover under £10.2m, under 50 employees), the IR35 determination still sits with you as the contractor.

Contract Vs Reality: The Critical Issue

A contract with all 14 clauses above does not protect you if the actual working arrangement contradicts them.

HMRC's compliance team will ask:

• Have you ever actually used the right of substitution, or is it just theoretical?
• Do you work 9–5 in the client's office every day like an employee?
• Are you supervised and managed exactly like a staff member?
• Have you ever worked for other clients during this engagement?

The contract and the reality must align. The checklist above is only useful if your working arrangements genuinely reflect it.

FAQ

Does having an IR35-friendly contract mean I'm automatically outside IR35?

No. HMRC looks at the actual working arrangements, not just what the contract says. If you sit in the client's office nine to five every day under close supervision, a contract clause saying you can work anywhere will not save you. Contract and reality must align.

Who determines IR35 status in 2026?

For medium and large private sector companies, the end client determines IR35 status and issues a Status Determination Statement. For small companies (turnover under £10.2m, fewer than 50 employees), the responsibility still sits with the contractor.

Can a client refuse to put IR35-friendly clauses in a contract?

They can, but refusal to include substitution or right-of-control clauses is itself an IR35 indicator. If a client insists on a contract that reads like employment, that is worth raising before signing.

Should I use HMRC's CEST tool?

CEST (Check Employment Status for Tax) is HMRC's online tool for assessing IR35 status. It is not perfect and famously does not assess mutuality of obligation, but HMRC will stand by its result if you use it accurately. Running CEST on every new engagement is good practice.

What happens if I am found to be inside IR35?

You will owe income tax and National Insurance on your gross contract fees for the relevant period, minus allowable expenses. HMRC can investigate up to 6 years back (20 years if they suspect fraud). This can run to tens of thousands of pounds for a long-term inside-IR35 engagement.