There are four main types of bid rigging: bid suppression, complementary bidding, bid rotation and subcontracting. In the most common of these schemes, complementary bidding, some of the "competitors" submit offers that they know the buyer will reject because the price is too high or the terms are unacceptable in order to create the appearance of legitimate bidding while ensuring that a prearranged "competitor" will win the bid.
The Office of Fair Trading has today formally accused 112 construction firms in England of participating in bid rigging.