Customs and Excise was due to announce a shortlist of six contracts to run three service packages that would build an IT infrastructure for the Lorry Road User Charge scheme.
Technology under consideration includes road-side detectors, in-vehicle transmitters and satellite-based systems.
A spokesman for Customs and Excise said, "We are looking at a big contract and we have been asked by the bidders to carry on the debriefing process. There are three service packages and discussion centres on how the companies will fit into those packages and work with HM Customs."
Brain Haney, director of research at consultancy Input, said the Lorry Road User Charge scheme was particularly complex and required a variety of suppliers with different technical expertise to work together.