What should you do if every contractor bid looks suspiciously alike?

Ask each bidder to explain its numbers, and look for signs beyond similar totals before you report anything. The Justice Department's Antitrust Division lists bid forms with identical calculations or spelling errors, or similar handwriting, typeface or stationery, among situations to be alert for, and says such indicators are not proof of collusion.

Source: U.S. Department of Justice, Antitrust Division, Price Fixing, Bid Rigging, and Market Allocation Schemes: What They Are and What to Look For (primer, revised February 2021), read 22 October 2026.

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By InstaBids editorial team with AI research agents. Sources read: 22 October 2026 Updated 2026-10-22

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Key facts

DOJ Antitrust Division primer on bid rigging: "Essentially, competitors agree in advance who will submit the winning bid on a contract being let through the competitive bidding process."
Source: U.S. Department of Justice, Antitrust Division, Price Fixing, Bid Rigging, and Market Allocation Schemes: What They Are and What to Look For (primer, revised February 2021), read 22 October 2026.
DOJ Antitrust Division primer, on bid forms: "The proposals or bid forms submitted by different vendors contain irregularities (such as identical calculations or spelling errors) or similar handwriting, typeface, or stationery. This may indicate that the designated low bidder may have prepared some or all of the losing vendor’s bid."
Source: U.S. Department of Justice, Antitrust Division, Price Fixing, Bid Rigging, and Market Allocation Schemes: What They Are and What to Look For (primer, revised February 2021), read 22 October 2026.
DOJ Antitrust Division primer, on indicators of collusion: "While these indicators may arouse suspicion of collusion, they are not proof of collusion."
Source: U.S. Department of Justice, Antitrust Division, Price Fixing, Bid Rigging, and Market Allocation Schemes: What They Are and What to Look For (primer, revised February 2021), read 22 October 2026.
DOJ Antitrust Division reporting page: "Antitrust Reports can be submitted online, by mail, or phone."
Source: U.S. Department of Justice, Antitrust Division, Report Antitrust Concerns to the Antitrust Division, read 22 October 2026.

What does the Justice Department mean by bid rigging?

An agreement on who wins: the Antitrust Division says that, essentially, competitors agree in advance who will submit the winning bid on a contract being let through the competitive bidding process. Its primer, revised February 2021, gives the full definition quoted below in its own words.

The Antitrust Division's primer, Price Fixing, Bid Rigging, and Market Allocation Schemes: What They Are and What to Look For, read 22 October 2026, says: "Bid rigging is the way that conspiring competitors effectively raise prices where purchasers — often federal, state, or local governments — acquire goods or services by soliciting competing bids." The next paragraph begins: "Essentially, competitors agree in advance who will submit the winning bid on a contract being let through the competitive bidding process."

The primer's introduction says: "Price fixing, bid rigging, and other forms of collusion are illegal and are subject to criminal prosecution by the Antitrust Division of the United States Department of Justice."

One form it describes is the bid that is never meant to win: "Complementary bidding (also known as “cover” or “courtesy” bidding) occurs when some competitors agree to submit bids that either are too high to be accepted or contain special terms that will not be acceptable to the buyer." It goes on: "Such bids are not intended to secure the buyer’s acceptance, but are merely designed to give the appearance of genuine competitive bidding."

In our reading, the signs in the primer are a reason to ask questions about the bids on a home job, not a test that settles whether those bids were rigged.

Which bidding details and statements does the Antitrust Division flag?

The paperwork itself: the primer lists bid forms from different companies that share irregularities, such as identical calculations or spelling errors, or similar handwriting, typeface or stationery, and says this may indicate that the designated low bidder may have prepared some or all of the losing vendor's bid. The item is quoted below in its own words.

Under the heading Suspicious Statements or Behavior, the primer says: "Be alert for the following situations, each of which has triggered a successful criminal antitrust prosecution:" The first item reads: "The proposals or bid forms submitted by different vendors contain irregularities (such as identical calculations or spelling errors) or similar handwriting, typeface, or stationery. This may indicate that the designated low bidder may have prepared some or all of the losing vendor’s bid."

The same list includes this item: "A company submits a bid when it is incapable of successfully performing the contract (likely a complementary bid)."

Listen for talk about the other bidders. Among the statements the primer lists are any statement indicating advance (non-public) knowledge of competitors' pricing and any statement indicating that vendors have discussed prices among themselves; three of its items are quoted below.

The primer's list of what a bidder or salesperson makes includes, in its own words: "Any statement indicating advance (non-public) knowledge of competitors’ pricing." "Statements that a bid was a “courtesy,” “complementary,” “token,” or “cover” bid." "Any statement indicating that vendors have discussed prices among themselves or have reached an understanding about prices."

In our reading, a remark like that is worth writing down with the date and the name of the company that said it.

Do matching prices prove the contractors worked together?

No. The primer says its indicators are not proof of collusion and merely call for further investigation, and it says identical prices may indicate a price-fixing conspiracy, especially in three situations; these passages are quoted below.

Under A Caution About Indicators of Collusion, the primer says: "While these indicators may arouse suspicion of collusion, they are not proof of collusion." It gives an example: "For example, bids that come in well above the estimate may indicate collusion or simply an incorrect estimate."

It also says: "Also, a bidder can lawfully submit an intentionally high bid that it does not think will be successful for its own independent business reasons, such as being too busy to handle the work but wanting to stay on the bidders’ list." And: "Only when a company submits an intentionally high bid because of an agreement with a competitor does an antitrust violation exist." Then: "Thus, indicators of collusion merely call for further investigation to determine whether collusion exists or whether there is an innocent explanation for the events in question."

Its price item reads: "Identical prices may indicate a price-fixing conspiracy, especially when:" The three conditions that follow, in its own words: "Prices stay identical for long periods of time." "Prices previously were different." "Price increases do not appear to be supported by increased costs."

The primer adds a condition about the market itself: "Collusion is more likely to occur if there are few sellers."

How do you report a bid you think was rigged?

Report it to the Antitrust Division's Complaint Center. Its reporting page says antitrust reports can be submitted online, by mail, or phone, that you are not required to include your name and contact information, and that the Division cannot give you legal advice; its words are quoted below.

Source: U.S. Department of Justice, Antitrust Division, Report Antitrust Concerns to the Antitrust Division, read 22 October 2026.
Source: U.S. Department of Justice, Antitrust Division, Report Violations, read 22 October 2026.

The Division's Report Violations page, read 22 October 2026, says: "Information from the public is vital to the work of the Antitrust Division." It also says: "To report general antitrust law violations or competition concerns, contact the Complaint Center."

Source: U.S. Department of Justice, Antitrust Division, Report Violations, read 22 October 2026.

The Complaint Center page, Report Antitrust Concerns to the Antitrust Division, read the same day, says: "Antitrust Reports can be submitted online, by mail, or phone." It adds: "Please keep in mind that the Antitrust Division cannot give you legal advice."

Source: U.S. Department of Justice, Antitrust Division, Report Antitrust Concerns to the Antitrust Division, read 22 October 2026.

On what happens next, the same page says: "You are not required to include your name and contact information when you submit your report." And: "We cannot let you know if we start an investigation because it is confidential."

Source: U.S. Department of Justice, Antitrust Division, Report Antitrust Concerns to the Antitrust Division, read 22 October 2026.

What can you look at yourself before you report anything?

Ask questions of the bidders first and keep every paper, because a close match can have a plain cause, such as every bidder pricing the same written scope. This is practical reasoning, not legal advice and not a finding from any agency.

Ask each bidder for a line-by-line breakdown of labor, materials, permit and cleanup, and ask how it arrived at each figure.
Lay the bid forms side by side. Note any shared calculation, the same misspelled word, or the same layout and typeface on papers from different companies.
Ask each company how it heard about your job and whether anyone else asked it to bid.
Invite one more company you found on your own, from outside the group that already bid. The primer's list of bid patterns includes: "Bid prices drop whenever a new or infrequent bidder submits a bid."
Source: U.S. Department of Justice, Antitrust Division, Price Fixing, Bid Rigging, and Market Allocation Schemes: What They Are and What to Look For (primer, revised February 2021), read 22 October 2026.
Write down, with the date, anything a bidder says about the other bids or about who should get the job.
Keep the original bids, envelopes and emails unchanged. Do not confront the bidders with an accusation.
If what you found goes beyond similar totals, send it to the Antitrust Division's Complaint Center, and contact your state attorney general's office if you want to know whether state law also applies.

Who sees your contact details when you post on InstaBids?

Contact details stay hidden until the homeowner picks a contractor and they confirm the connection.

Source: InstaBids process and privacy, live-page excerpts, read 22 October 2026.

Post your job on InstaBids, and contractors can bid in writing on one written scope.

Homeowners anywhere in the US can post a job; once you send it, InstaBids finds contractors to bid on it.

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