What counts as a week for the purposes of the 12-week qualifying period under the Agency Workers Regulations 2010?

Under the Agency Workers Regulations 2010 (SI 2010/93), an agency worker who works in the same role with the same hirer for 12 calendar weeks will qualify for equal basic terms and conditions of employment as a directly recruited employee in the same job. For the purposes of calculating the 12-week qualifying period, any week during which the agency worker works on the assignment is counted as a calendar week. For example, if an agency worker works for one day a week on an assignment, after 12 weeks they will have completed the qualifying period.

A calendar week is any period of seven days, with the qualification period starting on the first day of the assignment.