4.21 There should be a high degree of confidence that the PFI project is affordable, both before going out to market and during the procurement itself. It is crucial that cost assessments submitted at OBC are realistic. Any problem with affordability that arises late in the procurement process will increase transaction costs and undermine private sector confidence in the procurer and prejudice the procurer's ability to achieve VfM. Therefore, it is vital that in designing specifications that procuring authorities are mindful of their affordability envelope.