Definition
Retainage is the portion of every progress payment that the paying party holds back rather than releasing, kept in reserve until the work is finished and accepted. On a heavy-civil job, an owner withholds retainage from the general contractor, and the GC in turn withholds the same kind of reserve from each subcontractor. The point is leverage: the unpaid balance gives the GC a financial reason for a sub to come back, punch out the last items, and close the work rather than walking once the easy production is done.
For a GC evaluating the bids it receives, retainage is a contract term that shapes what a sub's price really means. A bid quoted against 10% retainage carries a different cash-flow burden — and a different risk of mid-job abandonment — than the same dollar figure quoted against 5% or none at all. The withheld balance is typically released at substantial completion, sometimes in stages, and is distinct from a bid bond, which guarantees the bid itself rather than the finished work.
A worked example
You award a drainage package to a sub for $800,000 with 5% retainage. The sub bills $200,000 in the first month; you pay $190,000 and hold back $10,000. After four months of even progress the full job is billed, and you have released $760,000 while withholding $40,000 in retainage. That $40,000 sits unpaid until substantial completion. If the sub leaves catch basins unfinished, you hold the balance — enough to bring in another crew to finish the punch list without paying twice. Push retainage to 10% on the same contract and the held-back reserve doubles to $80,000, tightening the sub's cash flow but widening your protection.
Why it matters when you evaluate sub bids
On a package with 5 to 15 bidders, retainage terms are part of what makes one price comparable to another. A sub that prices against heavy retainage may pad its unit prices to cover the carrying cost, or front-load its early line items to recover cash sooner — both of which distort a side-by-side comparison if you only read cover-sheet totals. A bid that ignores the retainage your contract requires is not quoting the same deal as one that accounts for it, so leveling the field means reading those terms, not just the numbers. Retainage also informs the award decision itself: a thinly capitalized low bidder carrying a large withheld balance is a higher abandonment risk, and that belongs in the record when you defend the award.
How Bid Reasoner handles it
Bid Reasoner scores the bids across six dimensions — price, scope, schedule, compliance, performance, and risk — though it has no retainage-specific check. Its four deterministic pricing rules catch the patterns retainage often produces: front-loaded mobilization at 10% or more of total, unbalanced unit prices at or under $1.00, peer outliers at 2x or more or 0.5x or less of the pay item's median (3+ bids), and total-bid outliers 20% or more off the median total (3+ bids). The two-way scope-coverage gap analysis checks each bid against your full scope by pay-item code, and when you weigh a low bidder's cash-flow risk against a safer price, decision modes such as Lowest Risk and Best Value let you make and defend that call — with the AI's ranking rationale captured in the generated Word documents.