Your bonding capacity is not set by your annual revenue, your reputation, or how long you have worked with your agent. It is set, month to month, by what a surety underwriter reads in your work-in-progress schedule. The WIP schedule is the document that determines the largest bond you can get and the total bonded work you can carry at once — and most contractors hand it over without knowing which columns the underwriter is actually interrogating.
This post takes the underwriter's seat. It walks the four specific questions a surety answers when they open your WIP, names the column each question reads from, and shows — with a real surety's worked example — how one column can quietly inflate your numbers and then get disallowed. The framing is capacity, not compliance: the WIP is not paperwork you owe the bond company. It is the lever that expands or shrinks your access to bonded work.
What does your WIP schedule actually tell a surety underwriter?
Your WIP schedule tells a surety underwriter what is happening in your business right now — not at the fiscal year-end your financial statements describe. The surety reads the WIP as "the framing" on top of the financial-statement "foundation," using it "to understand what is actually happening in your business right now, not six months ago when your fiscal year ended" (Projul). The financials prove you were solvent in December; the WIP proves you are solvent in June, with the current backlog, margins, and billing position on every open job.
That current-state read is what determines your bonding capacity — and bonding capacity is two numbers, not one:
- The single-job limit is the largest individual bond a surety will write. "If your single-job limit is $2 million, you cannot bond a $3 million project no matter how much aggregate room you have left" (Projul).
- The aggregate limit is the total value of all bonded work you can carry at once. "If your aggregate is $5 million and you already have $4 million in bonded backlog, the surety will only consider bonding another $1 million in new work" (Projul).
Neither number is fixed. This is the part contractors miss: "A bad quarter can shrink your capacity. A strong year-end statement can expand it" (Projul). And the document that signals a bad quarter — before the financials ever catch up — is the WIP. A surety bond is, at bottom, credit: "A bond is essentially a line of credit backed by the surety's financial strength and your promise to repay" (Projul). The WIP is the document that sets the size of that credit line.
That is why the WIP is worth getting right. The schedule, built on percentage-of-completion under ASC 606, is the same document your CPA builds your reviewed or audited financials around — and the underwriter expects the two to agree.
What are the four questions your underwriter is answering when they open your WIP?
A surety underwriter reads your WIP schedule to answer four specific questions: are your jobs profitable, are you billing accurately, are you overextended, and are your cost estimates reliable (Projul). Every surety weights them differently, but the four questions recur. Each maps to a column on your schedule, and a weak answer in any one of them — profit fade, growing underbillings, backlog crowding your aggregate limit, or a climbing estimated cost to complete — affects the bonding capacity the underwriter will extend.
Here is the framework, mapped to the WIP column each question reads from:
- Are your jobs profitable? → The projected gross-margin / gross-profit column. The underwriter scans for profit fade — a margin that has slipped from the bid number as the job has progressed. A row that opened at 12% and now reads 4% is the row they ask about.
- Are you billing accurately? → The over/under-billing column. Persistent over-billing late in a job borrows cash against unfinished work; growing underbilling ties up your liquidity and, as shown below, can inflate your working capital with money you may never collect. (The full mechanics live in over/under billing in construction.)
- Are you overextended? → The cost-to-complete backlog, read against your aggregate limit. The remaining cost on every open bonded job, totaled, is your committed capacity. When that total crowds the aggregate limit, there is no room for new work.
- Are your cost estimates reliable? → The estimated-cost-to-complete (ETC) trend across consecutive WIP periods. A cost estimate that holds steady reads as reliable. One that climbs every period reads as an estimate that was wrong from the start.
The contractor's edge: every question is answerable before you submit, and three of the four are about a single number moving the wrong way over time. The underwriter is not grading a snapshot; they are grading a trend.
How does a surety read available bonding capacity straight off your WIP?
The underwriter reads your remaining bonding capacity directly off the WIP, on a cost-to-complete basis: they total the remaining cost on your open bonded jobs and subtract it from your aggregate limit. There is no separate calculation and no waiting for the year-end financials — the backlog math is right there in the cost-to-complete column. As Grit Insurance puts it: "If your aggregate limit is $8 million and your WIP shows $7.5 million in active bonded work on a cost-to-complete basis, the surety knows there is very little room for another project" (Grit Insurance).
Work the arithmetic: $8 million aggregate minus $7.5 million active leaves $500,000 of room. A contractor in that spot who needs to bond a new $1.2 million job is told no — not because the surety doubts them, but because the WIP says the room is not there. Keep that backlog number current and reconciled and you know the answer before you ask.
This is also why the WIP must reconcile with the financial statements. A disconnect between the two documents makes the underwriter distrust both. If your financials show a profit but your WIP shows jobs losing money, the underwriter cannot tell which document is wrong — so they discount both (Grit Insurance). The cost-to-complete column that drives your available capacity has to tie out to the financials your CPA signs — one number, two readers, the same number for both.
What in the WIP-to-WIP trend read destroys your credibility?
The fastest way to lose an underwriter's confidence is an estimated cost to complete that climbs on the same job, period after period. The underwriter does not read your WIP in isolation; they compare this month against last quarter and last year. A cost-to-complete that keeps rising does not read as "this job got harder" — it reads as "your estimate was wrong and you are still adjusting it after the fact." As Projul states it: "If your 'estimated costs to complete' keeps climbing on the same project, your original estimate was wrong and you are chasing the number. That destroys credibility" (Projul).
The mechanism is in the estimate at completion. The EAC is costs-to-date plus the ETC, and it is the denominator behind percent complete and earned revenue. When a project manager revises the ETC upward each close, the EAC climbs, percent complete falls relative to the revenue already recognized, and the margin fades. The underwriter sees the same job appearing on three consecutive WIPs with a higher cost-to-complete each time, and reads it as an estimating process that does not converge.
The contractor's defense is a stable, well-documented ETC. An estimate that holds — or that moves once, for a named reason like an approved change order, and then holds — reads as control. A note attached to the number ("includes $30K contingency for the outstanding sub claim") tells the underwriter you saw it coming. The number that drifts upward with no explanation is the one that costs you capacity. This is the same trend read a CPA runs on profit fade, and it is why the ETC is the credibility-critical input on the whole schedule.
How did underbilling distort one contractor's capacity? (NASBP / Old Republic Surety)
Underbillings — costs and earned profit in excess of billings — inflate working capital, and a surety will disallow underbilled amounts it doubts will ever be collected. In a published analysis by Old Republic Surety, reported through the NASBP Pipeline newsletter, underbillings inflated one contractor's working capital by nearly $3 million, overstating both its financial position and its qualifying surety program (NASBP). It is the most concrete picture of how a single WIP column quietly destroys bonding capacity — told by an underwriter, not a contractor.
Here is the worked example, with the exact figures from the source. One of the contractor's projects was 97% complete at year-end and carried $296,000 in underbillings. Six months later, with the same project 99% complete, the underbillings had grown to $419,000 — despite the job running at an ongoing loss. An underbilling that grows as a job nears completion and loses money is not a billing timing lag. It is revenue the contractor recognized but is unlikely to ever collect. As the analysis concluded, "this trend indicated a low likelihood of collection, leading to the disallowance of these amounts from the contractor's WC calculation" (NASBP).
Trace what that disallowance does. Working capital is the single most important number a surety underwrites on (more on that below). When the underwriter strips out the underbilled balances that will not convert to cash, the contractor's working capital — and the bonding program it supports — drops by close to $3 million. Nothing changed on the jobsite. The capacity evaporated entirely inside the WIP schedule, in the over/under-billing column.
The lesson for the contractor is the read in question 2 of the four-question framework. A surety treats the over/under-billing pattern as a health signal, not a bookkeeping detail. A growing underbilled balance on a job that is nearly done and losing money is precisely the pattern that gets disallowed — and the only way to catch it before the underwriter does is a current, reconciled WIP that surfaces the trend while there is still time to bill, approve the change order, or resolve the dispute. The surety's own advice to contractors is direct: "Leverage Technology — Use integrated accounting and project management software to maintain accurate and real-time job cost data" (NASBP).
What are the three Cs, and why is working capital the most important number?
Sureties underwrite on three things — character, capacity, and capital, the "three Cs" — and of those, working capital is the single most important number (Projul). Character is your track record; capacity is your operational ability to perform; capital is your financial strength, measured first by working capital — the liquidity that proves you can fund the work and absorb a bad job. The four-question WIP read is how the underwriter pressure-tests that capital number against what is happening on your jobs.
The rules of thumb give you a sense of the math, though every surety sets its own standards:
- Most sureties want working capital equal to at least 5–10% of annual revenue (Projul).
- "Many sureties will support $10 to $15 in backlog for every $1 of working capital" (Projul).
- One broker pegs single-project capacity at 5–10 times working capital (or net worth) for contractors with strong operations and a clean completion history (Winter-Dent).
- Many growing commercial GCs "aim for bonding capacity equal to 1.0–1.5 times annual revenue" at the aggregate level (ABC Carolinas).
Treat those as directional, not formulas. Working capital sits at the center because it is the number a distorted WIP can inflate and a clean WIP can defend. The $10-to-$15-of-backlog rule makes the stakes concrete: every dollar of working capital the underwriter disallows can cost you $10 to $15 of backlog you are allowed to carry. The WIP is where that working-capital number is built or broken.
Single-job limit vs. aggregate limit
The two limits answer two different questions, and the WIP feeds both. Here is the comparison:
| Single-job limit | Aggregate limit | |
|---|---|---|
| What it is | The largest individual bond the surety will write | The total value of all bonded work you can carry at once |
| What it controls | Whether you can bid one specific project | Whether you have room for any new work on top of your current backlog |
| How it is read off the WIP | Compared against the contract value of a single new job | Your total cost-to-complete backlog, subtracted from the limit, is your remaining room |
| Source | "If your single-job limit is $2 million, you cannot bond a $3 million project" (Projul) | "$8 million aggregate, $7.5 million active on the WIP… very little room for another project" (Grit Insurance) |
A job can fit comfortably inside your aggregate room and still be too large for your single-job limit — and a job small enough for your single-job limit can be one you have no aggregate room to take. The underwriter checks both, and both are read against numbers that live on your WIP.
How does a timely, accurate WIP expand your bonding capacity?
A current, accurate, frequently submitted WIP raises your bonding limits and speeds your approvals — directly. The mechanism is confidence: when the underwriter trusts the document, they extend more credit on it. As Grit Insurance states: "A clean, accurate, current WIP gives the surety confidence… That confidence translates directly into higher bonding limits and faster approvals" (Grit Insurance). A sloppy or outdated WIP does the opposite — it makes the underwriter discount every number on it.
Frequency is the lever most contractors leave unpulled. Sureties reward sending quarterly — ideally monthly — WIP updates proactively, even when no one asks. An unsolicited monthly WIP "builds confidence and gives the underwriter a real-time view of your business" (Projul). The contractor who sends a clean WIP every month, before the deadline, gets the limit increase approved without a meeting. The one who scrambles to assemble a stale WIP only when the agent asks watches their capacity sit flat.
If you want one concrete move this quarter: close your WIP monthly, reconcile it to the GL before anyone asks, and send it to your agent unprompted with a one-line note on any job whose ETC moved. That habit — not a stronger balance sheet — is the cheapest capacity increase available to you.
That is the capacity-not-compliance point, stated plainly: the WIP is the single most direct lever you have on the size of your bonded book. For the step-by-step monthly workflow to track and grow your capacity from this same document, see how to track and increase your bonding capacity.
Frequently asked questions
What does a surety underwriter look for in a WIP schedule? A surety underwriter reads your WIP to answer four questions: are your jobs profitable, are you billing accurately, are you overextended, and are your cost estimates reliable? Each maps to a column — the projected-margin column, the over/under-billing column, the cost-to-complete backlog, and the estimated-cost-to-complete trend across periods (Projul).
How is bonding capacity determined from a WIP schedule? Available aggregate capacity is read straight off the WIP on a cost-to-complete basis. If your aggregate limit is $8 million and your WIP shows $7.5 million in active bonded work, the surety knows there is very little room for another project (Grit Insurance). The WIP must also reconcile with your financial statements, or the underwriter discounts both documents.
What happens when estimated costs to complete keep climbing on the same job? It destroys credibility. Per Projul, if your estimated costs to complete keep climbing on the same project, your original estimate was wrong and you are chasing the number. The underwriter reads the trend across consecutive WIP periods, not a single snapshot, so a steadily rising ETC reads as an estimating process that does not converge.
How does underbilling affect bonding capacity? Underbillings inflate working capital, and a surety can disallow amounts it doubts will be collected. In an Old Republic Surety analysis, underbillings inflated one contractor's working capital by nearly $3 million; an underbilling that grew from $296,000 to $419,000 on a job running 97%-to-99% complete at a loss was disallowed from the working-capital calculation (NASBP).
What is the difference between a single-job limit and an aggregate limit? The single-job limit is the largest individual bond a surety will write; the aggregate limit is the total value of all bonded work you can carry at once. A project can fit your aggregate room and still exceed your single-job limit, and vice versa (Projul).
Why is working capital the most important number to a surety? Working capital is the single most important number a surety underwrites on, because it proves you can fund the work and absorb a bad job. Most sureties want working capital equal to at least 5–10% of annual revenue, and many will support $10 to $15 in backlog for every $1 of working capital (Projul).
How often should I send my surety a WIP schedule? Quarterly at minimum, ideally monthly — and proactively, even when not asked. Per Projul, unsolicited monthly WIP updates build confidence and give the underwriter a real-time view of your business, which Grit Insurance notes translates directly into higher limits and faster approvals.
How WIP Ready helps
The four-question read above is only as good as the WIP you hand over — and most finance teams still rebuild that schedule by hand in Excel every month, chasing each PM's estimate to complete over email. WIP Ready produces the bonding-ready ASC 606 schedule inside Procore: it pulls your Procore project financials, collects a structured, timestamped ETC from every PM on their phone with no login, and outputs the WIP in your surety's own template — every figure tracing to a Procore field or an attributed PM submission. It never calculates the ETC for you; the project manager owns that number, the way a surety expects. A clean, current WIP, submitted monthly, is the most direct lever you have on your bonding capacity. See how the workflow runs at wipready.com.
