When it comes to determining whether a contractor falls inside or outside of IR35, HMRC’s CEST tool (Check Employment Status for Tax) is one of the most talked-about resources. But what exactly is it, how does it work, and when should you use it?
What Is HMRC’s CEST Tool?
CEST (Check Employment Status for Tax) is an online tool created by HMRC to determine a worker’s employment status for tax purposes — in particular, whether the Off-Payroll Working Rules (IR35) apply to a specific engagement.
You can access the tool here.
When Should You Use the CEST Tool?
The IR35 determination tool should be used in the following scenarios:
- Recruiters or end clients should use it when placing a contractor in a new role
- Limited company contractors (PSC) may use it for personal checks, though the determination isn’t binding
- Umbrella company employees generally do not need to use CEST, as they’re already employed for tax purposes by the umbrella
If you’re unsure about a contractor’s employment status for tax or want to mitigate risk, CEST can help provide a defensible decision.
A contractor’s IR35 status is based on the following:
- Details of the contract
- The worker’s responsibilities
- Who decides what work needs to be done
- Who decides when, where and how the work is done
- How the worker will be paid
- If the engagement includes any corporate benefits or reimbursement for expenses
If you’re unsure about any part of the Check Employment Status for Tax (CEST) tool, HMRC’s Employment Status Manual is a useful resource. It provides in-depth guidance, examples, and a glossary to help you understand key terms and make informed decisions.
How to Use the CEST Tool?
Here’s a step-by-step guide on how to accurately use HMRC’s CEST Tool:
- Gather your contract details and working practices
- Go to the official HMRC CEST Tool
- Answer all questions honestly and accurately
- Save the result (PDF)
- Discuss the findings with your accountant or umbrella provider
Make sure to act on the result given; failing to act on a “deemed employed” result can lead to backdated tax bills, interest and penalties.
CEST Result Explained
Once completed, the tool will give you one of the following determinations:
- unable to make a determination (for employed or self-employed for tax purposes)
- self-employed for tax purposes for this work
- employed for tax purposes for this work
- off-payroll working rules (IR35) do not apply
- off-payroll working rules (IR35) apply
- unable to make a determination (for whether the off-payroll working rules apply)
What If the Answer Is ‘Unable to Determine’?
This typically means the working pattern is nuanced or doesn’t fit neatly. In that scenario:
- Partner with an Umbrella Company, especially when roles fall inside IR35
- Revisit and refine the answers, perhaps with client-specific context
- Review your working practices for clarity (e.g., substitute rights, direction of work)
What Happens If I Partner with Trafalgar Umbrella?
If CEST confirms IR35 applies—or leaves it unclear—Trafalgar Umbrella provides a secure, PAYE-based employment solution:
- You become an employee of Trafalgar Umbrella under PAYE.
- We handle all tax, NIC, and HMRC reporting.
- You gain full statutory benefits (holiday, sick, pension, etc.).
- Your administrative burden is removed—we submit data, payroll runs, and timesheets.
- You enjoy ongoing HR support and customer care
If you join Trafalgar Umbrella, you also have access to our Gold Standard. This plan provides you with all the standard benefits as well as £50,000 Death In Service, Medical & Dental Cash Plan and discounts at 120+ Top Brands.
So don’t wait, click here and view our plans today!