The aim of inventory taking in the Karlsruhe Tritium Laboratory is to know at which time and place which amount of tritium is to be found in the laboratory. This paper describes for the first tritium delivery and the corresponding transfer to the tritium storage how to manage this problem. Segregation ist done between amounts of tritium which are available, bound and lost. It is shown where this fractions of tritium will be found and how to determine their quantities.