The implementation of quantitative surveys is often outsourced to survey institutes in the context of research projects. The services are then usually put out to tender in order to obtain offers from various institutes. As a rule, the invitation to tender includes a description of the services to be provided. The aim of these guidelines is to support the preparation of a detailed description of services for the tendering of interviewer-registered surveys. The focus of the guide is on the invitation to tender for personal oral interviews, but it can also serve as a basis for the invitation to tender for telephone interviews.