Accounted IR35 Assessment Tool Protects Contractors

IR35 is one of the biggest concerns for UK contractors, and getting the determination wrong can cost you thousands of pounds in unexpected tax. Yet many contractors either ignore IR35 entirely, relying on hope rather than analysis, or spend hundreds of pounds on professional assessments for every engagement. Accounted's IR35 assessment tool provides a middle ground: a structured, intelligent evaluation that helps you understand your position without the cost of a bespoke review.

In this article, I will explain how the tool works, what it covers, and how it fits into your broader IR35 compliance strategy.

Why Contractors Need an Assessment Tool

The off-payroll working rules require someone to determine whether each contracting engagement falls inside or outside IR35. For engagements with medium and large private sector clients (and all public sector bodies), the client makes this determination. For small private sector clients, the responsibility falls on your personal service company.

In both cases, having your own assessment is valuable. If the client determines you are inside IR35, you need to understand whether that determination is reasonable before deciding whether to challenge it. If you are responsible for the determination, you need a structured approach to get it right.

HMRC's CEST tool is the government's free option, but as I explain in my guide to CEST, it has significant limitations — including the failure to properly assess mutuality of obligation and a high rate of "undetermined" results.

Accounted's IR35 assessment tool addresses these gaps while remaining accessible and straightforward to use.

How the Assessment Tool Works

The tool guides you through a series of questions covering the established employment status tests. Unlike CEST, which uses simplified yes/no questions, our tool allows for more nuanced responses that reflect the reality of contracting engagements.

Control Assessment

The tool examines the degree of control your client exercises over your work. It considers:

• Who decides how the work is done (methods and approach)
• Whether you set your own working hours or follow the client's schedule
• Where you perform the work (your choice vs client requirement)
• Whether the client supervises your work in progress or reviews finished output
• Whether you can decline specific tasks within the engagement

Each factor is assessed on a scale rather than as a binary, giving a more accurate picture of the control dynamic. The tool weights these factors based on how the tax tribunals have historically treated them.

Substitution Assessment

The substitution section examines whether you have a genuine right to send someone else to do the work:

• Does your contract include a substitution clause?
• What conditions attach to the right (client approval, qualifications, etc.)?
• Have you ever exercised the right or discussed it with the client?
• Are there suitably qualified people who could substitute for you?
• Who would pay the substitute — you or the client?

For a deep understanding of why these questions matter, read my article on IR35 and substitution.

Mutuality of Obligation

Unlike CEST, our tool properly assesses mutuality of obligation — a factor that the tax tribunals consistently consider:

• Is the client obligated to provide you with work beyond the current project?
• Are you obligated to accept additional work from the client?
• Could either party walk away without notice or penalty?
• Is the engagement project-based with defined deliverables, or ongoing and open-ended?

Financial Risk

The tool evaluates whether you bear genuine financial risk in the engagement:

• Do you provide your own equipment and tools?
• Do you carry professional indemnity insurance?
• Could you make a financial loss on the engagement?
• Are you responsible for correcting defective work at your own cost?
• Is payment based on deliverables or on time spent?

Integration Assessment

Finally, the tool considers how integrated you are into the client's organisation:

• Do you attend staff meetings or social events?
• Do you have a client email address, building pass, or desk?
• Are you included in organisational charts or directories?
• Do you receive employee benefits or participate in employee programmes?

Understanding Your Results

After completing the assessment, you receive a clear result: likely outside IR35, likely inside IR35, or borderline. Each result comes with a detailed explanation of which factors contributed most strongly to the determination and where your position is strongest or weakest.

For borderline cases, the tool highlights the specific areas where small changes to your working practices or contract could shift the balance. This actionable guidance is one of the key advantages over CEST, which simply returns "undetermined" without further help.

The tool also generates a summary report that you can save for your records. If HMRC ever queries your status, this report demonstrates that you took reasonable care in your assessment — an important factor in mitigating potential penalties.

What the Tool Is Not

It is important to understand the tool's limitations:

It is not legal advice. The tool provides an informed assessment based on the established tests, but it is not a substitute for professional legal advice on complex or high-value engagements.

It is not binding on HMRC. Unlike CEST (where HMRC has committed to standing behind the result), Accounted's tool does not carry HMRC's endorsement. However, it demonstrates reasonable care and provides a more thorough analysis.

It is not a one-time exercise. Your IR35 status should be reassessed whenever your engagement changes — new client, new contract terms, or significant changes in working practices.

According to HMRC's guidance, taking reasonable care in making status determinations is a key factor in avoiding penalties.

How the Tool Fits into Your IR35 Strategy

I recommend using the assessment tool as part of a layered approach to IR35 compliance:

First layer: Self-assessment. Use the tool to evaluate each new engagement. This gives you a baseline understanding of your position and highlights areas that need attention.

Second layer: Contract review. Based on the assessment results, review your contract to ensure the terms support your desired position. My guide on IR35-compliant contracts covers the key clauses.

Third layer: Evidence gathering. Document your working practices to support your assessment. Keep records of instances where you exercised control, used substitution, or operated independently of the client.

Fourth layer: Professional review (where needed). For high-value engagements, borderline cases, or complex situations, invest in a professional IR35 review. The assessment tool's results can help you frame the discussion with the specialist and may reduce the cost of their review.

For a complete step-by-step guide to the assessment process, read my article on how to determine your IR35 status.

Beyond IR35: Complete Contractor Financial Management

IR35 status is just one piece of the contractor financial puzzle. Accounted helps you manage the entire picture:

Income tracking — Monitor your contract income in real time, with clear breakdowns by client and project.

Expense management — Track and categorise business expenses, scan receipts via WhatsApp, and maximise your tax deductions.

Tax calculations — Get real-time estimates of your income tax, National Insurance, and corporation tax liabilities. I update your projections as your income and expenses change throughout the year.

Self-assessment filing — When it is time to file, your self-assessment return is largely prepared from the data already in the system. No January panic.

MTD compliance — Quarterly submissions and digital record-keeping are handled automatically, keeping you compliant with Making Tax Digital requirements.

Getting Started

If you are a contractor, start by assessing your current engagement using the tool. It takes about ten minutes and gives you immediate clarity on your IR35 position.

Then, explore how Accounted can manage the rest of your contracting finances. From bookkeeping to tax filing, I am here to handle the numbers so you can focus on delivering excellent work for your clients.

As IPSE emphasises, contractors who proactively manage their IR35 status and maintain good records are in a far stronger position if HMRC enquires.

Visit our pricing page to find the right plan for your contracting business, and sign up today to get started.

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