What is retainage?
Retainage is a percentage of each payment, commonly 5 to 10%, that an owner or general contractor withholds until the project is complete. It is intended as security that the work will be finished and defects corrected, and it is released at or after final completion.
The cash flow effect
Retainage is withheld from your margin, not from your cost. You still pay labor, material and equipment in full while 5 to 10% of every payment is held back, so the amount withheld frequently exceeds the profit on the job.
On a $10 million project at 10%, that is $1 million not reaching your account until final completion and punch list sign-off, which may be a year or more after you began. Contractors who fund operations on a revolver carry a real interest cost on that balance for the whole period.
Receivable and payable
Two sides of the same mechanism, and they appear separately on your books.
Retainage receivable is money your customers are withholding from you. It is an asset, though an illiquid one, and lenders discount it accordingly.
Retainage payable is money you are withholding from your own subcontractors. It is a liability, and it is also a cash management tool: a contractor holding retainage on subs while having retainage held on them has a partially offsetting position.
Where it goes wrong
Retainage is the most commonly under-tracked balance in construction accounting. It accumulates quietly across many jobs, and because release depends on completion events rather than a schedule, nobody is watching a due date.
The practical failure is not that retainage exists. It is that balances from finished jobs sit unclaimed for months because no one is chasing the release. An aged retainage report, reviewed alongside the WIP, is usually the fastest cash recovery available to a contractor who has never run one.