Bid rigging occurs when government officials preparing the contract, perhaps in conspiracy with a local or foreign company, ensure through a device or scheme that the contract is ultimately awarded to the designated bidder.  This generally occurs when government officials secretly, or not so secretly, decide who will win the bid.

Bids come in far above the agency's estimate for the value of the contract or far above comparable bids by the same companies in other areas;

A winning bidder subcontracts part of the business to one or more losing bidders;

There is some indication of a physical alteration of bids, particularly at the last minute;

Particular line items for some bidders are much higher than for others (no relation to cost);

The range of bids shows a clear gap between the winner and all others (an indicator of a number-to-bid-above situation);

The bids of all companies are very close (an indicator that bidders knew each others' prices);

All companies submit high bids when work is known to be scarce;

The company gives different bids for the same line item on different contracts that are close in time;

The companies appear to have engineered a split of the contract by each bidding low on some aspect of it and inexplicably high on other parts;

There is physical evidence of collusion, such as different companies submitting bids with the same handwriting, or in the same envelopes, or with the same mathematical or spelling errors, or from the same fax number;

Qualified bidders do not bid, especially if they initially took steps to bid;

If a contract is re-bid because all initial bids are unacceptable, the bidders come back in the same order or some bidders fail to re-bid;

There are significant increases by most bidders over previous prices when there have been no substantial cost increases;

A bidder mysteriously declines signing a contract;

Prices mysteriously drop when a new bidder appears on the scene.