Bias corrections in primary frequency standards

Primary frequency standards serve the function of calibrating the rate of International Atomic Time, TAI, and therefore play a critical role in the accuracy of the world´s time. The Working Group on Primary and Secondary Frequency Standards, WGPSFS, is an advisory body to the Time Department of the Bureau International des Poids et Mesures and to the Consultative Committee for Time and Frequency on matters related to primary and secondary frequency standards that are used to determine the rate of TAI. A current issue being considered by the WGPSFS is establishing guidelines for deciding when and how to make corrections for newly discovered frequency biases in primary frequency standards. This paper is intended to generate discussions on this topic in an audience wider than just the WGPSFS.