To ask the Chancellor of the Exchequer, pursuant to the Answer of 11 July 2018 to Question 160282, what specific methods of testing have been used to assess the accuracy of the Check Employment Status for Tax; and whether regression testing has been used on that system.
7 September 2018
The Check Employment Status for Tax (CEST) service is designed to determine whether an existing or future contract will be one of employment or self-employment.
The CEST digital service was rigorously tested throughout development, in accordance with government data standards and with input from external stakeholders, prior to release. The accuracy of CEST was checked as part of that process. Results have been tested by HM Revenue and Customs (HMRC) against known case law and settled cases.
HMRC continues to work with stakeholders to understand their experiences of CEST and ensure that it works effectively.
HMRC will stand by the result of CEST, provided the information entered is accurate and in line with HMRC guidance. CEST gives an answer in 85% of cases, and where it does not, people can call a dedicated HMRC helpline staffed by specialists who can give them further advice.
HMRC has published its position on Mutuality of Obligation (MoO), and how it interacts with the CEST service: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/722316/HMRC_paper_on_Mutuality_of_Obligation.pdf
HMRC has published the list of cases that were used to test the accuracy of CEST: https://www.gov.uk/government/publications/cest-tool-tested-against-tax-cases