The Regulations refer to an agency worker as:
an individual;
who is supplied by a temporary work agency to work temporarily under the supervision and direction of a hirer; and who
has a contract of employment with the agency, or any other contract with the agency to perform work or services personally.
You will not be an agency worker if:
you have found a permanent job (even if this is via an agency); or
- you are genuinely self-employed (i.e. in business on your own account).
If you are an agency worker, you cannot opt out of the Regulations.