Your Bonding Capacity Is a Math Problem

Your bonding capacity is not a relationship. It's an arithmetic output, and the arithmetic runs on numbers you produce. Plenty of owners treat the surety like a lender to be charmed. The surety treats your financial statement like a math problem, and the answer to that problem is how much work you're allowed to chase.

Here's the math most owners never see laid out plainly. Sureties commonly support somewhere between ten and $15 of backlog for every dollar of working capital, and they set an aggregate program, meaning your total bonded backlog at once, at roughly 15 to 20 times working capital. Underwriters want to see working capital running around 7 to 10 percent of the cost to complete your backlog for a subcontractor, and at least 5 percent for a general contractor. Those ratios decide your single-job limit and your total limit. Everything else is commentary.

Working capital is the number, and billing sets it

Working capital is current assets minus current liabilities. Simple enough. The trap is that how you bill moves it, and most contractors move it the wrong way without noticing.

Overbilling feels like winning. You billed ahead of the work, cash came in early, the job funded itself. On the balance sheet that money sits as a liability, billings in excess of costs, because you owe work you've already collected for. Lean on overbilling across several jobs and you've inflated your current liabilities, which pushes working capital down, which lowers the very capacity you were trying to protect. You ran your business on the customer's dollar and told the surety you're weaker than you are.

Underbilling is the other face of the same coin, and it's usually worse. Work you've performed but not billed shows up as an asset, costs in excess of billings, but it's cash you already spent and haven't collected. Large underbillings tell a surety one of two things. Either your billing process leaks, or you've got jobs fading and you're sitting on cost you can't bill because the work is in dispute. Neither reading helps you.

The schedule tells the surety who you are

I have sat across the table from owners at bond renewal, watching an underwriter turn straight to the work-in-progress schedule and read the business off it in about four minutes. Not the P&L. The WIP. Job by job, it shows gross margin holding or fading, it shows the over and under billings, it shows whether one customer is half your backlog. Underwriters have a name for what they're grading, the three C's, capital and capacity and character. The WIP schedule is where all three show up at once, because a clean, consistent, accurate schedule is itself evidence of character.

An inconsistent schedule does more damage than a merely weak one. Margins that swing job to job with no story behind them. An over-billing position that reverses for no reason. Numbers that don't tie back to the financials. The underwriter can't tell whether you're hiding something or simply don't know your own costs, and from a risk seat those look identical. Credibility, once it's gone, prices into every bond you write afterward.

Capacity you can actually reach

Backlog is competitive right now. The Associated Builders and Contractors put its Construction Backlog Indicator at 8.1 months in early 2026, which reads as healthy demand and also as more contractors bidding for bonded work to reach it. Capacity you can't access does nothing for you in that fight.

So run the numbers the surety runs, on your own schedule, before they do. Bill in step with the work instead of ahead of it, so your working capital reads true. Keep retained earnings inside the company rather than distributing to the edge of the ratio, because equity is the cheapest bonding capacity you'll ever hold. And produce a WIP schedule every month that you'd hand an underwriter without flinching. Do that and your capacity becomes a number you control. Skip it and it stays a number that gets decided about you.