This Practice Note provides an overview of the compulsory jurisdiction of the Financial Ombudsman Service (FOS). The compulsory jurisdiction of the FOS is defined in Chapter 2 of the Financial Conduct Authority (FCA) Dispute Resolution: Complaints Sourcebook (DISP), in rules made pursuant to section 226 of the Financial Services and Markets Act 2000 (FSMA 2000), which provides that a complaint which relates to an act or omission of a person (the respondent) should be dealt with under the FOS scheme, providing certain conditions apply.