Fundamentals

Bid Rigging: What It Is, How It Works, and Why It Harms Competition

By Daniel Sardá · Published on October 13, 2026

7 min read1,330 words

A tender can look competitive without being so. This guide explains how coordination among bidders distorts the process, the forms it can take, and how to distinguish a warning sign from proof.

A tender is meant to compare proposals and identify the one that offers the best terms. But receiving several sealed bids, documents, or prices does not guarantee competition. If the participants agreed beforehand on who would win or how they would submit their bids, the rivalry is only apparent.

Bid rigging occurs when two or more bidders secretly coordinate their decisions instead of competing independently. The agreement may concern the price, the winner, the territories served, customers, or even the decision to participate. It is also called bid manipulation and can arise in both public and private procurement, although the applicable rules and legal consequences vary by country.

Key idea: a tender is not competitive simply because it receives several bids. What matters is that each participant has determined its bid independently.

How coordination replaces competition

In a genuine tender, every business faces uncertainty: it does not know exactly what price its rivals will offer and must decide how far it can reduce costs, improve quality, or take on risk to win. That pressure allows the buyer to compare real alternatives.

Bid rigging removes some of that uncertainty for those involved in the agreement. Bidders may decide who will submit the attractive proposal and what the others will do to avoid competing for the contract. The buyer still sees a formal procedure, but no longer obtains the outcome of independent decisions made under economic competition and social cooperation.

The problem is not simply that several firms know the market or respond in similar ways. In sectors with common inputs, highly detailed requirements, or few suppliers, bids may resemble one another without any agreement. The central question is whether coordination has replaced decisions that should have been made separately.

Four common forms

OECD guidelines describe four recurring schemes. They are not closed categories: a single agreement may combine more than one.

Cover bidding

One or more participants submit bids designed to lose. They may set a deliberately high price, include terms the buyer is unlikely to accept, or make an offer less favorable than that of the prearranged winner. Their role is to create the appearance of rivalry.

For example, three suppliers agree that one will win. The other two submit higher prices, not because that is their best independent commercial decision, but to make the preselected bid look competitive.

Bid suppression

A business agrees not to submit a bid, to withdraw one, or to refrain from competing so that another can win. Absence alone does not prove an agreement: a company may lack the capacity, financing, or interest to take on the contract. What matters is coordinated abstention.

Bid rotation

Participants take turns winning contracts. The rotation may follow a sequence, allocate awards by size, or try to balance revenue over time. Any one tender may look ordinary; the pattern becomes visible when several calls for bids are examined.

Market, customer, or territory allocation

Businesses agree not to compete in particular areas, for particular buyers, or for particular types of contract. Each thereby keeps a protected space. Rather than contesting open opportunities, they limit entry and the buyer's choice among themselves.

Key idea: the visible form may differ—a high bid, a withdrawal, a turn, or a reserved area—but the mechanism is the same: deciding together what should have been decided under rivalry.

Why it harms the buyer and the market

When bids are independent, competition puts pressure on each bidder to justify its price and improve its proposal. Bid rigging weakens that discovery process. It can lead to a higher award price, fewer options, lower quality, or worse service terms. There is, however, no universal percentage of overcharge that applies to every case.

The effect can reach beyond a single purchase. If potential entrants perceive that customers or territories have been divided up, they have less incentive to enter. And if the process is designed with unnecessary requirements or makes it easy for bidders to anticipate their rivals' conduct, coordination can be easier to sustain.

From the perspective of economic freedom, the harm does not come from businesses seeking profit, but from their suppressing rivalry through an agreement. An open market needs freedom of entry and independent business decisions, not privately predetermined outcomes behind a competitive façade.

Signs that warrant review, not condemnation

Bid rigging is usually secret, so buyers and authorities look for patterns in documents, prices, and conduct. Possible signs include:

• unusually identical mistakes, formats, or expressions in different bids;
• bids that appear designed to lose;
• unexpected withdrawals or repeated absences;
• awards that regularly alternate among the same participants;
• competitors that stop bidding in particular areas or for particular customers;
• the losing bidder later subcontracting for the winner when the context is difficult to explain.

Nothing on this list proves an agreement by itself. Similar prices may reflect shared costs; mistakes may come from a common template; a tender may draw few participants because the market is small or the requirements are demanding. Even subcontracting may answer a legitimate technical need.

The prudent approach is to examine sets of indicators and patterns over time, retain relevant information, and refer the matter to the appropriate authority when warranted. Turning an indicator into a verdict does not protect competition; it replaces analysis with suspicion.

Warning: a sign is useful for asking questions and reviewing the context. Proof of coordination requires additional evidence, and the applicable standard depends on the jurisdiction.

It is not the same as corruption or legitimate cooperation

Bid rigging and corruption can coexist, but they describe different relationships. In bid rigging, bidders who should compete coordinate with one another. In corruption, a person breaches duties owed to the process—for example, through bribery or the misuse of decision-making power. Knowing who is coordinating with whom helps prevent the concepts from being confused.

Nor is every business collaboration collusive. A consortium or joint bid can bring together complementary capabilities and enable participation by businesses that could not perform a contract alone. The European Commission's horizontal cooperation guidelines stress that subcontracting does not by itself create a general presumption of collusion.

The useful question is whether cooperation makes a viable bid possible or eliminates competition that would actually have existed between the parties. The answer depends on their capacity, the degree of integration, the market context, and the applicable law.

How to reduce risk without closing off entry

In public procurement, prevention begins with a design that encourages participation and makes coordination harder. This can involve researching the market before issuing a call for bids, defining clear and proportionate requirements, avoiding unnecessary restrictions, and reviewing bidding patterns from earlier processes.

Careful information management also matters. Transparency enables accountability, but disclosing certain sensitive information at the wrong time can help participants monitor compliance with an agreement. There is no single formula: the design should fit the market, the subject of the contract, and the specific risks.

Adding procedures indiscriminately does not guarantee better outcomes. If a rule excludes capable suppliers without sufficient justification, it may reduce the competitive pressure it was meant to protect. Safeguards work best when they preserve entry, require independent bids, and make patterns detectable without presuming guilt.

Real rivalry is what gives a tender its purpose

A sound tender is not measured only by compliance with formal steps. Its value lies in bringing together genuine alternatives and enabling the buyer to discover better terms through competition. Bid rigging empties that mechanism by replacing independent decisions with an agreed outcome.

Recognizing its forms helps us look beyond appearances; distinguishing indicators from proof avoids hasty accusations; and separating useful cooperation from anticompetitive coordination preserves opportunities for entry. Legal characterization, investigation, and any sanction always depend on the rules and authorities of the relevant jurisdiction. The economic principle, however, is general: without real rivalry, a tender no longer serves its purpose.