How retainage works in construction — and how to bill retainage releases correctly

Retainage is simple to describe and easy to get wrong: a percentage of every payment is withheld until the work is complete, and released later. The withholding part takes care of itself. The release — getting that money back, at the right time, without breaking the math on every subsequent application — is where subcontractor billing most often falls apart. This article covers both halves.

What retainage is and why it exists

Retainage (also called retention) is a contractually agreed percentage — commonly 5% or 10% — withheld from each progress payment. Owners and GCs hold it as security that the work will be finished and defects corrected; it also keeps leverage in the relationship until punch-list items are closed out. The percentage, the base it applies to, and the conditions for release all live in your subcontract, so read those clauses before your first application — not at closeout.

Two wrinkles worth knowing: many contracts apply a different (often lower, sometimes zero) rate to stored materials than to completed work — that’s why the G702 splits retainage into lines 5a and 5b. And retainage is regulated: many states cap rates or mandate release timing, especially on public projects, and rules differ between public and private work. Check the statute in your state rather than assuming your contract’s terms are the last word.

How retainage flows through the G702/G703

On each application, retainage is computed on the cumulative totals, not on this month’s billing alone:

• Line 4 is your total completed and stored to date (cumulative).
• Line 5 is retainage on that cumulative total — 5a on completed work, 5b on stored materials.
• Line 6 (total earned less retainage) = Line 4 − Line 5.
• Line 7 subtracts what was previously certified, and Line 8 is the payment due.

Because everything is cumulative, the retainage withheld this month is implicit: it’s the growth in Line 5 from last application to this one. You never bill “minus 10% of this month’s work” directly — the cumulative structure does it for you. This matters because it means any change to the retainage rate or a release of held retainage changes Line 5, and therefore ripples into Line 6, Line 7 on the next application, and every application after that.

When retainage comes back

Releases typically happen at one of three points:

1. Final completion. The classic case: work is done, punch list closed, and the final application bills remaining contract balance plus all held retainage.
2. Substantial completion / rate reduction. Many contracts step retainage down mid-project — for example from 10% to 5% once the work is substantially complete, releasing the difference. Public-work statutes in some states require reductions like this.
3. Negotiated early release. On long jobs, subs sometimes negotiate a release of part of the held amount while work continues.

Release is rarely automatic. Expect conditions: punch-list completion, final or conditional lien waivers, consent of surety where there’s a bond, closeout documents, warranties. Track these per project — retainage that nobody invoices for has a way of never arriving.

How to bill a release correctly

The cleanest practice — and what many GCs require — is to bill a retainage release as its own application, separate from new work. Some GCs will not accept retainage and new work billed in the same month at all. A release application looks unusual but follows the same arithmetic:

• No new work: column E is zero on every line.
• Line 5 (retainage held) decreases — to the new lower amount, or to zero on a full release.
• Line 6 therefore increases even though Line 4 didn’t move, and Line 8 (payment due) equals exactly the retainage being released.

Then come the two rules that keep the job reconciled afterward:

Rule 1: The next application’s Line 7 must include the release

Line 7 (“less previous certificates”) on any application must reflect everything previously certified — including interim retainage releases, not just the last regular progress application. If your spreadsheet builds Line 7 by copying Line 6 from the previous progress app and ignores the release that happened in between, you will re-bill the released money on your next application. The GC’s accountant will catch it — or worse, they won’t, and it surfaces as a dispute at closeout.

Rule 2: Never re-bill released retainage after a rate change

After a reduction (say 10% → 5%), new work bills at the new rate, but your cumulative Line 5 must reflect the reduced holding — and every subsequent application must remember that the difference was already paid out. This is the single most error-prone scenario in AIA billing, because it breaks the tidy pattern of “this month’s Line 7 equals last month’s Line 6” that most spreadsheets are built on.

A worked example

Say your contract is $500,000 with 10% retainage, and you’re 60% complete ($300,000 earned):

• Retainage held (Line 5): $30,000
• Earned less retainage (Line 6): $270,000 — all previously paid.

The GC agrees to reduce retainage to 5% at substantial completion. Your release application holds Line 4 at $300,000, drops Line 5 to $15,000, so Line 6 rises to $285,000. Less previous certificates of $270,000 leaves $15,000 due — the released half.

Next month you bill $50,000 of new work. Line 4 becomes $350,000; Line 5 is now 5% × $350,000 = $17,500; Line 6 is $332,500. Line 7 must be $285,000 — the prior progress application’s Line 6 plus the $15,000 release. Payment due: $47,500. Use $270,000 instead and you’d claim $62,500 — re-billing the released $15,000, and handing the GC a reason to bounce the application.

Retainage and your cash flow

At 10% retainage, a sub running 10% gross margin is effectively financing the job interest-free until release. That’s why retainage discipline is cash-flow discipline: know how much is held on every project, know the contractual release triggers, bill reductions the month they’re earned, and invoice final retainage with your closeout package instead of weeks later. Money you don’t apply for is money the GC is in no hurry to send.

The takeaway

Withholding retainage is arithmetic; releasing it is bookkeeping across time. Every release changes the baseline that all future applications reconcile against, which is exactly the kind of cumulative, cross-document dependency that spreadsheets handle badly and purpose-built billing systems handle automatically. However you run your billing, make sure the release path — separate release applications, Line 7 that includes interim releases, rate reductions that stick — is something your process does by construction, not by memory.