Check Employment Status for Tax (CEST) is HMRC’s free online tool that gives HMRC’s view of whether a specific engagement is employment or self employment for tax and National Insurance, or whether the off payroll working rules apply. HMRC stands by the result if the answers are accurate and the tool is used in line with its guidance. It does not test mutuality of obligation: it simply asks whether a contract exists, because HMRC treats any contract for work and pay as meeting that requirement.

What is CEST for and who can use it?

HMRC’s guidance on GOV.UK says the tool can be used to check whether a worker should be classed as employed or self employed for tax, to find out whether the off payroll working (IR35) rules apply, to test whether a change to a contract or working arrangement alters the result, and to check a result already given. Anyone can use it: hirers, workers, agencies or other third parties. ESM11006 explains that the questions and outcome are the same whether you answer as worker or hirer; only the wording changes. A hirer that does not yet know who the worker will be gets fewer questions and a result HMRC will stand by, but HMRC recommends running the tool again once the worker is known.

Using CEST is not compulsory (ESM11015). It is anonymous, does not save progress and does not store results, so the user must download or print the output.

What does the tool ask?

Before starting, HMRC says you need details of the contract, the worker’s responsibilities, who decides what work is done and when, where and how it is done, how the worker is paid, and whether the engagement includes corporate benefits or expenses. The questions then follow the case law factors described in our guide to the employment status tests:

  • Office holder. If the worker will hold an office, CEST concludes employed for tax, because office holders are always taxed as employees (ESM11035).
  • Contract. Whether there is, or will be, a contract in place (ESM11036).
  • Personal service. Whether the client can reject a substitute, whether the worker would pay a substitute, and whether the worker hires and pays helpers.
  • Control. Who decides what the worker does, how, when and where (ESM11060). It is the right of control that counts, and manuals, policies and management hierarchies can show it.
  • Financial risk. Significant costs for equipment, vehicles, materials and other items that the worker must bear under the contract without reimbursement, how the worker is paid, and whether they must put work right at their own cost (ESM11085).
  • Part and parcel. Corporate benefits, management responsibilities and how the worker is introduced to customers and suppliers (ESM11120).
  • Business on own account. Exclusivity, ownership rights, series of contracts, how much of the worker’s available working time the work takes, and similar work in the last 12 months (ESM11140 to ESM11165).

What results can CEST give?

ESM11170 lists six possible outcomes: the off payroll rules apply; they do not apply; unable to determine whether they apply; employed for tax purposes for this work; self employed for tax purposes for this work; and unable to determine employed or self employed. Each result shows the answers given and the reasoning. Where CEST cannot decide, HMRC points users to further guidance, its helpline or a suitably qualified adviser.

When will HMRC stand by the result?

ESM11010 says HMRC will stand by the determination if the information is accurate and the tool is used in accordance with HMRC guidance. Three qualifications follow:

  • if contractual or working arrangements later change materially, the original answers may no longer be accurate and HMRC will not stand by the old result;
  • HMRC will not stand by results reached through contrived arrangements designed to get a particular outcome, which it treats as deliberate non compliance with a risk of penalties;
  • a result based on what the contract says, when practice is different, is not an accurate input.

For the off payroll rules, the output has a formal role. GOV.UK says the result can be used as a valid status determination statement, and ESM10013 says an accurate CEST output can constitute a valid statement provided the statutory conditions are met. ESM10014 lists accurately completing and applying CEST results as an example of the reasonable care a client must take, and inputting inaccurate information as an example of failing to take it.

Why does CEST not test mutuality of obligation?

The only mutuality question is whether there is, or will be, a contract in place. ESM11036 explains that answering no stops the tool, and answering yes lets you continue but does not affect the determination. HMRC’s position, set out at ESM0543, is that mutuality of obligation determines only whether any contract exists: the engager must pay and the worker must provide their own work. Any engagement where work is done for pay meets it.

That approach was long criticised. ICAS reported in 2020 that the Upper Tribunal in the PGMOL referees case had rejected HMRC’s argument that mutuality only determines whether a contract exists, and noted that CEST had not been configured to consider it. The Supreme Court then decided HMRC v Professional Game Match Officials Ltd [2024] UKSC 29. HMRC cites it in ESM11036 as reaffirming that the basic requirements are an obligation to pay and an obligation to provide one’s own work, and ESM0543 records the Court’s view that a single engagement can be employment even without an overarching obligation to offer or accept more work.

A gap remains. ESM0543 also accepts that the nature and extent of mutual obligations can be factored into the overall evaluation. CEST has no question that captures, for example, a worker’s freedom to turn down further assignments, so that kind of evidence only influences the outcome indirectly through other answers.

What other limits does the tool have?

  • It is for tax and National Insurance only and should not be used for employment rights (ESM11006).
  • HMRC says it should not be used for agency workers who do not work through an intermediary, for managed service company workers outside the public sector, for deciding whether someone in a partnership or LLP is a partner or a salaried member, or for apprentices, Crown servants and contracts of training. Agency workers have their own rules.
  • Some answers are wider than a lawyer might expect. Under ESM11045 a client has a right to reject a substitute if the contract is silent on substitution, if substitutes must come from a pre approved pool, or if substitution would not be practical or plausible, for example because of security vetting or short timescales.
  • Costs count as financial risk only if they are significant, required by the contract and not reimbursed. Everyday items and low value consumables are ignored (ESM11085).

How does a substitution answer play out in practice?

Illustration only. A client engages a contractor’s company for a two week data migration. The contract allows a substitute, but adding anyone to the client’s secure systems takes two weeks. Following ESM11045, substitution is not plausible, so the honest answer is that the client can reject a substitute. If the client also sets the tasks and the deadline but not the method, and the contractor bears no significant costs, CEST may return employed or unable to determine. Changing the answer on substitution to reach a different result would not be an accurate input, and HMRC would not stand by it.

How should CEST be used in practice?

  • Answer from the contract and from what actually happens, and gather the facts before starting because progress cannot be saved.
  • Keep the PDF output with the contract. CEST stores nothing, so it is your only evidence of the answers given.
  • Run it again when the role, contract or working practices change.
  • Where the result is unable to determine, or the facts are finely balanced, apply the case law directly and take advice. An IR35 enquiry will test the facts behind the answers, not just the output.

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Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 8 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.