HMRC Revises CEST as IR35 Status Checks Face Renewed Scrutiny
HMRC has updated its employment status tool for the first time in more than four years, but contractors and tax specialists say the changes improve presentation without resolving the deeper uncertainty surrounding IR35 decisions.
HM Revenue and Customs revised its Check Employment Status for Tax tool at the end of April, making the update one of the principal IR35 developments facing UK contractors in May 2025.
CEST is used by contractors, recruitment agencies and hiring organisations to decide whether an engagement should be treated as employed or self employed for tax purposes. When completed by a client, its result can be retained as a Status Determination Statement.
The revised service introduced simpler language, additional links to HMRC guidance and a new opening requirement that a contract must exist or be expected. HMRC says that contract can be written, verbal, implied or a combination of these forms. HMRC’s revised CEST guidance was published on 30 April.
New presentation, old decision logic
The most important limitation was what HMRC did not change. The underlying decision logic remained the same, meaning an assessment completed before the update should theoretically produce the same result afterwards, provided the contract and working practices have not changed.
An HMRC spokesperson told contractor insurer Kingsbridge: “These changes do not affect how the tool determines if a worker is self-employed or employed.”
Contractors and clients were therefore not expected to repeat every previous assessment merely because the revised tool had appeared. HMRC said it would continue to stand behind results based on accurate information.
Nevertheless, contemporary analysis revealed continuing concern about the reliability of the service. Bauer & Cottrell reported that approximately 20 per cent of completed assessments produced an undetermined outcome. The status specialist said CEST could be useful within a wider compliance process but remained too basic to handle the full complexity of real working relationships. Its May analysis advised against relying upon the tool in isolation.
Dave Chaplin, chief executive of IR35 Shield, was more critical. Writing for AccountingWEB, he said the questions and decision logic had last been substantially updated in November 2019, despite numerous tribunal hearings and significant employment status judgments since then. He accused HMRC of “trying to fix its users” rather than repairing CEST itself. Chaplin’s analysis argued that users needed to study the revised manual carefully.
What the change meant for IT contractors
For IT contractors, the central lesson was that CEST remained only as reliable as the evidence entered into it. A carefully drafted substitution clause would carry little protection if the client would never accept a substitute in practice. Similarly, a contract describing an independent consultant could be undermined if the client controlled the individual like an employee or integrated them into an internal team.
The update therefore increased the importance of keeping contracts, project descriptions and actual working arrangements aligned. Contractors needed to retain evidence of project autonomy, financial risk, control over delivery and any genuine ability to provide a substitute.
For clients, particularly large organisations engaging teams of technology specialists, the revised interface did not remove the obligation to take reasonable care over each determination. Borderline or undetermined cases still required a fuller assessment rather than an automatic decision that placed every contractor inside IR35.
The update made CEST easier to navigate, but did not settle whether a digital questionnaire can reproduce the detailed evaluation performed by a tax tribunal.