Sigma Management Services SA | 85 followers on LinkedIn. Sigma Management Services has been operating in Switzerland since 1990 and in that time has built up a wealth of experience within the Swiss market. Our area of expertise is in the provision of recruitment support services, payroll/contract management, PEO, employer of record and fiscal compliance. Sigma holds both cantonal and federal labour leasing licences and with its team of international tax experts is able to assist individuals and companies within Switzerland and worldwide with the recruitment and management of expats and locals alike.