Retainage is a percentage of each progress payment, commonly 5 to 10 percent, that an owner or general contractor holds back until the project is complete and accepted.
On a $180,000 paving subcontract with 10 percent retainage, $18,000 builds up with the GC over the job. It comes back at substantial completion, at final acceptance, or when the owner releases the GC's retainage, depending on what the subcontract says. Some contracts drop the rate once the job is half done, and many states cap it or set release deadlines on public work.
For a paving sub whose work finishes early on a long project, retainage can sit for months after the crew leaves. Track it on every job as money you're owed, ask for release at completion of your own work when you negotiate, and check what your state requires when you hold retainage on your own subs.
In Pavr, retainage is held from the first pay app to the release, on a G703-style continuation sheet the GC's office will recognize.