Zellis is providing payroll, HR, and managed services to the UK and Ireland-based companies with over 500 employees. We are the largest business of this nature in the UK counting a third of the FTSE 100 as customers, serving over 5 million of our customers'​ employees, and processing in excess of 60 million payslips a year. The leading provider of HR, Payroll, Managed Services, Benefits, and Recognition solutions for the UK and Ireland.