CEST stands for the "Check Employment Status for Tax" tool. It is an online tool provided by the UK government that is designed to help individuals and businesses determine the employment status of workers for tax purposes.

The CEST status tool allows users to enter information about a worker's circumstances and receive an assessment of their employment status. The tool takes into account factors such as the degree of control that the worker has over their work, whether they are required to work set hours, and whether they are responsible for their own tax and National Insurance contributions.

The CEST status tool is intended to help individuals and businesses determine whether a worker is an employee, self-employed, or something else for tax purposes. It is important to accurately determine the employment status of workers, as it can have significant implications for tax and National Insurance contributions.