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

I get a version of this conversation almost every week from a contractor who just won their first big commercial project. They're celebrating. The bid landed at the price they wanted. The crew is mobilizing. They tell me how it's going to change everything.

Then I ask one question. "How much cash will you float between week one and the first GC payment?"

The answer is almost always: "I haven't actually run that number."

That's the conversation. Most first-time commercial subs underestimate the cash gap by a factor of 3-5x. They think the job is going to fund itself once the crew starts billing. The reality is that the math is structurally cash-negative for the first 6-10 weeks, and the gap is bigger than they think.

Here's the model, the specific 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.

For a $400K labor budget over 26 weeks, week-one payroll is roughly $15K. Month-one cumulative payroll is $60K. Month-two cumulative is $120K. Most owners think about it as "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 58-75 of the project. That's two months of payroll already out the door before the first dollar comes back in.

For the same $400K labor budget, day-58 cumulative payroll is roughly $120K. Day-75 is $145K. The owner is floating $120K-$145K just on labor before week 11 of the project.

3. 5% retainage withheld

The GC contract holds back 5% of every payment as retainage, released at substantial completion. On a $1.9M project, that's $95K sitting at the GC for the entire duration of the project, plus 30-90 days after completion before release.

The retainage isn't part of your peak cash gap, but it's a constant drag on working capital throughout the project. And subs who don't track retainage often forget to chase it after substantial completion. Industry average loss on un-chased retainage is 8-15%.

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.

For a project with $300K of material spend over the duration, the front-loaded portion (typically the first 60% of materials hits in the first 30% of the project) is roughly $180K of materials cost in the first 8-10 weeks. The cash for those materials shows up between weeks 14 and 20.

The $1.9M project, modeled

Putting all of that together for a $500K-revenue residential painter winning a $1.9M apartment-complex project on prevailing-wage rates:

These numbers are approximate but representative. The peak cash gap, in this scenario, is roughly $300K around week 12 of the project. 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 resist this on subs they haven't worked with before. But it's standard on infrastructure and large institutional work. Worth asking. The worst they can say is no.

Lever 2: Pay-when-paid clause negotiation

Default subcontract language has 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. If the owner doesn't pay the GC for any reason, the sub doesn't 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. Or better: get a personal guarantee from the GC for prompt payment.

Lever 3: Material credit terms with suppliers

Most paint and supply distributors will extend 60-day terms to commercial accounts on volume. Some will extend 75-day terms with personal guarantees. If your supplier's payment terms align better with your GC's payment cycle, the materials don't drive the cash gap.

For the example project, if the painter negotiated 60-day terms instead of 30-day, the peak cash gap drops from $300K to roughly $220K — a 27% reduction with one phone call.

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 cash gap (size your LoC to this, plus 30-day buffer)
• When the gap occurs (so you draw at the right time, not too early)
• When it recovers (so you pay down the LoC promptly to minimize interest)
• What the cost of capital actually is (LoC interest at 8% on $300K for 3 months is $6K, not $24K)

Without the model, owners typically over-borrow by 2-3x out of paranoia, take on extra interest cost they don't need, and 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 hasn't. Your CPA hasn't. 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.

Run a free cash gap model on your next bid or book a 30-min consult — we'll model your specific project week-by-week and tell you whether the math actually works.

Related reading

• How a $500K painter survived their first $1.9M 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