Why Profitable Contractors Run Out of Cash: Retainage, Growth, and the Gap Nobody Adds Up

Every job you finished last year made money. The estimates were close. The crews were productive. Your accountant says the year was profitable and he is not wrong.

And you have spent the last six months moving money around to make payroll.

This is the most common thing that happens to a growing commercial contractor, and it is not a contradiction. Profit and cash are two different measurements taken at two different moments. For most businesses the distance between them is a few weeks. In construction it is structural, and it has three specific causes you can name and measure.

The Three Places Your Profit Is Sitting

1. Retainage, held by agreement

Five or ten percent of every payment, depending on the contract, withheld until the work is complete. On one job it is an irritation. Across every open contract at once it is frequently a larger number than the owner would guess, and it is close to pure margin, because your costs on that work were paid in full months ago.

Most contractors have never seen the total. It gets folded into accounts receivable, where it sits alongside genuinely current invoices and disappears into an aging report that treats it as merely slow.

2. Underbillings, or work you did and did not invoice

If you have performed more work than you have billed, the cost left your account and the revenue has not arrived. On a work-in-progress schedule this shows up as costs and earned revenue in excess of billings.

Underbillings are the quietest of the three, because nothing about them feels like a problem. Nobody is chasing you. The job is going well. You are simply funding somebody else's project out of your own working capital, and you will keep doing it until the billing catches up.

3. The working capital the next job consumes

Every contract requires you to spend before you collect. Materials, subcontractor payments, payroll, mobilisation. On a job the size of your last one, you know that number in your bones. On a job materially larger, you do not, and the requirement arrives months ahead of the revenue.

What This Looks Like on a Real Job

A mechanical sub who had been running three or four contracts at a time won a job roughly double the size of anything he had taken before. Good general contractor, good scope, a margin that justified the risk. The kind of award that changes what a business is.

The sequence that followed is the one worth understanding, because none of it is a mistake:

• Material had to be ordered and paid for well ahead of installation.
• His own subs invoiced him on their terms, which were shorter than the GC's terms to him.
• Payroll ran every week regardless of where the billing cycle sat.
• The first pay application went in at the end of the month, was reviewed, was certified, and was paid on the GC's cycle after that.
• Ten percent of it was retained.

He was profitable on the job the entire time. He was also, for several months, the cheapest lender that general contractor had. The line of credit that had comfortably covered a business running three smaller contracts was not sized for one running this. Nothing about the job was wrong. The financing of it was never planned, because on every previous job it had never needed to be.

Why Your P&L Will Not Warn You

A profit and loss statement built for a tax return reports what happened over a period. It has no opinion about whether the money arrived, and on a long contract it may not even report the right revenue, because revenue on a job in progress depends on how complete the job actually is.

That is what a work-in-progress schedule exists to do. Cost-to-cost percent complete compares what you have spent against what you expect to spend, converts that into how much revenue you have genuinely earned, and compares it against what you have billed. The difference in either direction is the number that matters.

Read the wrong way round, a profitable month looks like a crisis, or a loss stays invisible until closeout. Read correctly, a WIP schedule tells you which jobs are actually funding the business and which are quietly being funded by it.

The Signals That Show Up Before the Crunch

• You cannot say what your retainage totals across open contracts without opening the books. If it takes an afternoon to find out, it is not being managed.
• Underbillings are growing month over month. Billing is falling behind production, and the gap is being financed by you.
• The line of credit no longer goes back to zero. A facility that used to clear between jobs and now carries a permanent balance has quietly become working capital.
• Payables are stretching while the jobs still look profitable. This is the first externally visible symptom, and suppliers notice before you decide to act.
• You are bidding to keep cash moving rather than because the work fits. Bidding for cash flow rather than margin is how a busy year turns into a bad one.
• Your bonding capacity has not moved despite a good year. A surety reading a stale or underbilled WIP schedule will not extend capacity, which caps the work you are allowed to chase.

What Actually Closes the Gap

Most of the fix is measurement, because you cannot manage a balance you have never totalled. The rest is sequencing.

• Total your retainage and age it by contract. Not as a lump. By job, with the release condition each contract actually specifies.
• Report retainage separately from current receivables. Different balance, different behaviour, different decision. Mixing them hides both.
• Run a WIP schedule monthly, not at year end. Cost-to-cost percent complete, over and under billings identified and explained, with a roll-forward showing what moved and why.
• Bill to production. Most underbilling is a paperwork lag rather than a dispute. If the schedule of values is maintained and the pay application goes in complete and on time, the gap closes on its own.
• Chase closeout like it is money. Final lien waivers, warranties and as-builts are frequently the only thing between you and a retainage release.
• Size the facility before you need it. A line of credit is far easier to arrange from a clean WIP schedule and a good year than from a cash crisis, and the terms are not comparable.
• Model the next job before you sign it. The question is not whether the margin is good. It is whether you can fund the months between mobilisation and the first certified payment.

The billing half of this is covered in detail in how contractors get paid faster. The forecasting half sits in the 13-week cash flow forecast, which is the right horizon for a contractor because it covers a full billing cycle plus the lag.

The Reporting That Prevents This

None of the above requires a finance department. It requires four numbers, current, in one place, every month: percent complete and over or under billings, retainage position by contract, contract margin against estimate, and cash against profit.

A contractor who has those four in front of him on the eighth business day does not get surprised by a cash crunch, because the crunch announces itself a quarter early. That reporting is what we run for commercial contractors, and it is described on the page for commercial contractors and for subcontractors working under a GC.

About the Author

Tom Woolley, MBA

Tom Woolley is a fractional CFO who spent six years running job costing and logistics in construction before founding Today CFO. He works with commercial subcontractors and small general contractors on the reporting a GC and a surety actually read.

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