What to Do When a Subcontractor's Bid Looks Too Low to Trust

The number lands in your inbox and it’s $140,000 under the next bidder. Everyone in the room wants it to be real. The instinct is to use it, protect the spread, and sort out the details in buyout. That instinct has cost GCs hundreds of thousands of dollars on jobs that looked profitable at award.

A low sub number is not a gift. It’s a question that hasn’t been answered yet. The way you handle it in the next 24 hours determines whether it saves you margin or destroys it.

The Four Reasons a Number Comes In That Far Under the Field

There are only a few reasons a number comes in that far under the field. The sub missed scope. The sub priced the wrong set of drawings. The sub is buying the work intentionally and plans to recover on change orders. Or, occasionally, they’re actually more efficient than everyone else and the number is real.

The first three happen far more often than the fourth. Start there.

Call the sub the same day, not to negotiate, but to compare scope. Walk through the major line items out loud. Ask specifically what their number includes for items you know are expensive on this job. Ask about exclusions before they volunteer them, because the ones they don’t mention are the ones that will surface at buyout. If they’re missing 15% of the scope and don’t know it yet, you need to know that now, not six weeks after award.

Also check the drawing revision. Subs quoting off superseded drawings is more common than it should be. If Addendum 3 added $80,000 in scope and the sub never opened it, their number will look like a gift right up until you hand them the contract.

Plug In That Number and You’ve Already Made a Decision

A lot of estimators will use the low number in the estimate and flag it as a risk. That is not protection. That’s deferring a problem into a document that an owner is going to rely on, and it’s a decision, whether you treat it as one or not.

Do your own rough scope check before the number touches your estimate. You don’t need a full quantity takeoff. You need enough to know whether the sub’s price is in a plausible range. If your internal benchmark for this scope is $420,000 and the sub is at $280,000, the gap is $140,000. That’s not a rounding error. Something is wrong.

If you can’t reconcile the gap through the scope call, price it two ways. Submit with the low number and document it clearly as unverified, with a specific contingency line covering the exposure. Or use the next closest number and note it in your clarifications. The bid clarifications list you bring to the owner meeting is exactly where this kind of flag belongs. Don’t bury it in a cell.

When the Revised Proposal Shows Up Three Weeks Into Buyout

You award the scope. Three weeks into buyout, the sub sends a revised proposal. The new number has an exclusions page. Equipment pads: excluded. Crane picks over 5 tons: excluded. All work above the second floor assumes separate hoist access provided by others. The revised number is $412,000.

Now you’re $132,000 over the awarded contract value, the owner has your number locked, and you’re the one explaining why the budget moved. The sub didn’t lie to you. They quoted what they quoted. You just didn’t verify it.

This scenario is predictable and preventable, and it’s common enough on jobs where a single trade bid was a significant outlier that you should treat it as a default risk, not an edge case.

The sub who is buying the work with a low number is a separate problem. They know exactly what they submitted. Their plan was always to recover the margin through RFIs, change order requests, and scope disputes once they’re locked in. The only real defense against this is a thorough contract with scope exhibits that mirror what they priced, signed before you award. No assumptions. No handshakes. Scope in writing.

A low number deserves scrutiny proportional to how far it is from the field. That’s not pessimism. That’s how you protect a margin that took months to build.

Comms Center keeps full communication history with every sub in one place, so when you need to go back and verify what was discussed on a scope call, it’s there. You can also track which subs have submitted, which are still outstanding, and flag trades where you’re relying on a single number that hasn’t been verified. Learn more at commscenter.com.