From $7K Jobs to $1.9M Jobs: The Cash Math Nobody Warns You About

Picture an owner who just won their first big commercial project. They're celebrating. The bid landed at the price they wanted. The crew is mobilizing. This job is going to change everything.

The first question to ask is how much cash you will float between week one and the point where GC payments catch up with your costs.

If nobody has run that number yet, the bid is not ready.

It is tempting to assume the job will fund itself once the crew starts billing. In the fictional model below, cumulative cash first turns positive briefly after the month-five GC receipt (around week 22), then dips to about -$156,750 before the month-six receipt. It stays positive from the end of month six (around week 26). The trough is close to the shop's entire annual residential revenue.

Here's the model, fictional but internally consistent dollar amounts on a $1.9M project, and the three levers that change the answer.

The structural cash-negative period

A typical commercial subcontract has four payment timing rules that residential work does not. Each one delays cash inflow.

1. Weekly payroll vs. monthly billing cycle

You pay your crew weekly. You bill the GC monthly through the AIA pay application process. The labor cost outlay starts on day 7 of the project. The first invoice goes out on day 28-35. Right there, you're floating the entire first month of payroll before you've even billed for it.

In the fictional model below, payroll follows work in place on a $950,000 labor budget: $95,000 in month one (10% complete) and $237,500 cumulative by the end of month two. It is easy to think about weekly burn and lose sight of the cumulative number.

2. 30-day GC pay cycle after billing

The GC pay application is approved (or partially approved) and paid roughly 30 days after submission. Some GCs run 45 days. So your day-28 first invoice doesn't convert to cash until day 58-73 of the project. That's two months of payroll already out the door before the first dollar comes back in.

In the model, the first pay app goes in at the end of month one and is paid at the end of month two, around day 60. By then $237,500 of payroll and $120,000 of supplier payments are out the door, against a first receipt of $180,500 (95% of the $190,000 billed, after retainage).

3. 5% retainage withheld

The GC contract holds back 5% of every payment as retainage, released after substantial completion or closeout on the contract schedule and conditions. On a $1.9M project, that builds to $95K held by the GC by the final pay app, released after completion on whatever schedule the contract sets (the model assumes 90 days).

Retainage trims every receipt, so it widens the gap slightly during the project; in the model, $23,750 has been withheld by the end of month three. Its larger effect is that the last $95,000 arrives months after your costs are paid. Read the subcontract at signing for release conditions, required closeout documents and lien waivers, and any contractual or statutory notice and claim deadlines. Those dates override any internal aging playbook, so calendar them before the job starts and chase release on that schedule. This article does not cite a measured loss rate for un-chased retainage, so track your own unreleased retainage by job and age.

4. Materials front-loaded, AR back-loaded

Material orders for the project hit your line of credit in weeks 2-4 of the project. Paint, supplies, equipment rentals, scaffolding deposits. Your supplier wants payment in 30 days. The GC payment for the materials line item arrives 60-75 days later.

In the fictional model, $400,000 of materials is purchased front-loaded: 30% in month one and 25% in month two, so $220,000 is bought in the first two months while only 25% of the work is billable. Unless the contract lets you bill for stored materials, the GC pays for those materials only as the work is billed and paid, through months two to seven.

The $1.9M project, modeled

Putting all of that together for a fictional $500K-revenue residential painter winning a $1.9M apartment-complex project with prevailing-wage requirements. All assumptions are illustrative:

• Contract value $1,900,000, about six months (26 weeks) of work.
• Work in place by month: 10%, 15%, 20%, 20%, 20%, 15%. Each month-end pay app bills that share.
• 5% retainage on every pay app. The GC pays the other 95% 30 days after each month-end pay app. Retainage is released 90 days after substantial completion (end of month nine).
• Labor $950,000 (burdened, at prevailing-wage rates), paid weekly in line with work in place.
• Materials $400,000, purchased 30%, 25%, 15%, 15%, 10%, 5% by month, paid on 30-day supplier terms.
• Direct cost $1,350,000, so job gross profit is $550,000 (28.9%). Overhead, the owner's existing residential work, mobilization payments and line-of-credit interest are excluded.
• GC payments arrive on the last day of the month, after that month's payroll and supplier payments.

Inflows total $1,900,000 and direct costs total $1,350,000, so the $550,000 ending position equals the job's assumed gross profit. The peak cash gap in this fictional scenario is about $467,000 at the end of month three (around week 13), just before the second GC payment lands. Cumulative cash first turns positive after the month-five GC receipt, goes negative again (about -$156,750) before the month-six receipt, and stays positive from the end of month six. Change any assumption, such as percent complete, GC lag, retainage or the cost budget, and the peak moves. That is why you run your own numbers rather than borrowing these. The owner has to float that gap somehow before the project pays for itself.

The three levers that change the answer

The peak cash gap isn't fixed. Three negotiable items move the number materially:

Lever 1: Mobilization payment

Negotiate a mobilization payment in the contract. 5-10% of the contract value paid at notice-to-proceed, before any work is done. On a $1.9M project, that's $95K-$190K of cash arriving before week one of payroll.

GCs may resist this on subs they haven't worked with before. Mobilization is also often recouped from later pay apps, so it shifts timing rather than adding revenue. Fictional arithmetic: if $95,000 arrives at notice-to-proceed and is recouped evenly from the six pay apps (about $15,833 each), only one reduced receipt has landed by the month-three trough. The trough improves by about $79,167, to about -$387,833. Worth asking. The worst they can say is no.

Lever 2: Pay-when-paid clause negotiation

Some subcontracts contain a "pay-when-paid" or "pay-if-paid" clause that says the GC pays the sub only when (or if) the owner pays the GC. Pay-if-paid is much worse. Where it is enforceable, if the owner doesn't pay the GC, the sub may not get paid at all.

Negotiate the clause to "pay-when-paid within 60 days", so even if the owner is late, you're not floating the cash indefinitely. Enforceability of pay-if-paid and pay-when-paid clauses, and the deadlines in state prompt-payment and lien statutes, vary by state, so have construction counsel review the clause before you sign. Realistic asks include a defined outside payment date, joint checks for materials, and confirmation of whether a payment bond exists and what notice its claim path requires. Calendar any notice deadline at signing, because it overrides your internal collection schedule.

Lever 3: Material credit terms with suppliers

Ask your paint and supply distributors whether they offer 60-day terms to commercial accounts, and what credit application, volume or personal guarantee they require. Terms vary by supplier and by your credit history. If your supplier's payment terms align better with your GC's payment cycle, the materials don't drive the cash gap.

For the fictional project, moving the same purchases to 60-day terms gives month-end positions, just before each GC receipt, of -$95,000, -$237,500, -$367,000, -$386,250 and -$275,250 for months one through five. The peak moves to month four and drops from $467,000 to $386,250, a reduction of $80,750 (about 17%). Total material cost is unchanged; only timing moves.

The line of credit decision

Most owners approach this with "I need a line of credit" as the starting point. The right starting point is the model. The model tells you:

• The peak job cash gap (add overhead, interest, parallel work and a 30-day buffer before sizing funding)
• When the gap occurs (so you draw at the right time, not too early)
• When it recovers and the remaining forecast stays funded (repay only the cash the next payroll, AP and retainage delays will not need)
• What the cost of capital actually is (fictional sensitivity: $467,000 held constant for one-quarter of a year at 8% annual interest costs $9,340, before fees. Actual cost follows the dated draws and repayments: sum each outstanding balance × annual rate × days/365. A different draw duration can make total cost higher or lower than this sensitivity.)

Without the model, it is easy to size the line by gut feel, either too small to cover the trough or larger than needed with interest you didn't need to pay, and to miss the secondary working capital tools (mobilization payments, supplier terms) that would have reduced the gap in the first place.

I cover the LoC decision specifically in why a line of credit isn't the cash flow fix you think it is. The short version: an LoC is the second-best forcing function for cash discipline. The first is a real model.

What to do before your next big bid

If you're a sub looking at a commercial project that's 5x or more your average job size:

Action 1: Build the cash forecast before you finalize the bid. Project value, labor cost, material cost, payment timing, retainage. Run it week-by-week. Identify peak cash gap.

Action 2: Walk the model with someone who has seen first commercial projects before. Your bookkeeper or CPA may not have. Find a fractional CFO or experienced commercial-construction CFO, even for a paid one-hour consult. The cost of that hour is trivial compared to the cost of getting the bid wrong.

Action 3: If the model says you can't float the gap, either negotiate better terms (mobilization, materials credit) or pass on the bid. Walking from a project that would have killed you is the most underrated skill in commercial subcontracting.

Action 4: If you take the project, set up a weekly forecast through completion. Update every Friday. Track actuals against budget. The forecast is the product. The LoC is just the tool that lets you execute the forecast.

The math is simple. The discipline of running it is what separates the subs who scale into commercial work from the ones who get crushed on their first big job. You don't need a CFO firm to do this work, but you do need someone who has seen the pattern before, and you need to do it before the bid goes in, not after the first payroll bounces.

Start with the free find-your-gap tool or book a first call to discuss your project's assumptions and the records needed for a week-by-week cash model.

Related reading

• How a small HVAC contractor planned its first large commercial job, case study
• Davis Bacon prevailing wages: the hidden labor cost that sinks first-time commercial subcontractors
• Why a line of credit isn't the cash flow fix you think it is
• What the Level Index tells us about contractor cash flow during growth
• Your CPA files taxes, your bookkeeper closes books