5.16 If cost estimates at OBC differ significantly from the price at Full Business Case (FBC) or financial close, questions should be asked as to whether there are legitimate external reasons which could not be foreseen and, if not, why this escalation was not captured by the Optimism Bias estimates. This analysis should then be incorporated into the Optimism Bias estimates for forthcoming projects. This is not however a reason at this stage to halt or revisit the procurement decision. This information should be used to inform future procurements.
5.17 Under the Competitive Dialogue procedure, once a preferred bidder has been selected there should be no further amendments having the effect of modifying substantial aspects of the bid or which risk distorting competition or causing discrimination. Subject to any cost movements associated with a funding competition (see below), costs should therefore be fixed following preferred bidder selection.