HMRC guidance is issued on secondary contributor: special rules: the agency worker: on or after 6 April 2014. Paragraphs 2 & 9 of Schedule 3 Regulation 5 to the Social Security (Categorisation of Earners) 1978 (As amended by The Social Security (Categorisation of Earners) (Amendment) Regulations 2014 / Statutory Instruments 2014 No. XXXX)

Where a person is supplied by a foreign employer, or by or through an agency, there are special rules that determine who is the secondary contributor. The regulations treat someone in the United Kingdom (UK) as the secondary contributor. Find out more at http://www.hmrc.gov.uk/manuals/nimmanual/NIM33750.htm