Bonding Capacity Explained
Your bonding capacity is two numbers and a date, and it lives in a document most contractors have never read.
The letter of authority
When a surety approves your account, it does not want to underwrite every individual bond request. So it issues your producer a letter of authority — sometimes called an underwriting authority letter or a capacity letter — that states:
- Single job limit — the largest one contract the surety will bond without going back upstairs
- Aggregate limit — the total uncompleted bonded work you may carry at one time
- An expiration date — normally annual, tied to your financial statement cycle
Inside those limits your producer can issue bonds and prequalification letters immediately, under a power of attorney from the surety. Outside them, every request is a fresh underwriting decision.
This is why bond turnaround times are so bimodal. Inside the letter of authority, you can have a bond the same day. Outside it, you are waiting days or weeks while an underwriter looks at your job.
Ask your producer for a copy of your current letter of authority and its expiration date. You should know your two numbers the way you know your bank line. Most contractors do not, and they discover the limit by bumping into it three days before a bid.
The limits are a starting point, not a wall
Being over your single limit does not mean no. It means the request goes to the underwriter for a specific decision on that specific job. Sureties approve above-limit jobs all the time — for the right job, with the right owner, at the right margin, for a contractor with a good record.
What kills those requests is timing. An underwriter asked on Monday about a Thursday bid will say no because they have no time to get comfortable. The same underwriter given two weeks will often say yes.
If a job you want is above your single limit, tell your producer the day you decide to pursue it — not the day the bid is due. Two weeks of notice converts a reflexive no into a real conversation.
How the numbers get calculated
The rules of thumb
The common industry approximations:
| Limit | Typical multiple |
|---|---|
| Single job | ≈ 10 × working capital |
| Aggregate | ≈ 20 × working capital, or 10–20 × net worth |
Some sureties lead with net worth, some with working capital, most look at both and take the lower answer.
But it is really the ratios
Those multiples are the same statements as the capacity ratios an underwriter actually runs:
| Ratio | Target | Equivalent multiple |
|---|---|---|
| Working capital ÷ backlog over 10% | subcontractor | backlog under 10 × working capital |
| Working capital ÷ backlog over 5% | general contractor | backlog under 20 × working capital |
| Net worth ÷ backlog over 7% | backlog < ~14 × net worth |
Same rule, expressed as a ratio instead of a multiple.
And the working capital in those formulas is analyzed working capital, not the number on your balance sheet. This is where nearly every contractor's mental model diverges from their surety's. A company showing $1,080,000 of working capital can have $150,000 of analyzed working capital once related-party receivables, stale AR, inventory, prepaid items and underbillings are adjusted. See how sureties read your financials for the full adjustment schedule and a worked example.
Worked example
A subcontractor with:
- Analyzed working capital: $1,200,000
- Analyzed net worth: $2,800,000
| Test | Calculation | Result |
|---|---|---|
| Single job (10 × WC) | $1,200,000 × 10 | $12,000,000 |
| Aggregate (20 × WC) | $1,200,000 × 20 | $24,000,000 |
| Aggregate (10 × NW) | $2,800,000 × 10 | $28,000,000 |
| Aggregate — surety takes the lower | $24,000,000 |
In practice a first-time or newer account gets less than the formula suggests, and a long-standing account with a spotless record often gets more. The formula is where the conversation starts.
Aggregate is measured in cost to complete
This is the detail that most changes how you should manage your capacity, and it is consistently misunderstood.
Your aggregate limit is consumed by remaining cost to complete on bonded work, not by total contract value.
Worked example
| Job | Contract value | Cost incurred to date | Remaining cost to complete |
|---|---|---|---|
| A | $4,000,000 | $3,600,000 | $400,000 |
| B | $6,000,000 | $2,000,000 | $4,000,000 |
| C | $3,000,000 | $100,000 | $2,900,000 |
| Total | $13,000,000 | $7,300,000 |
You have $13M of bonded contracts on the books. You are consuming $7.3M of aggregate capacity, not $13M.
Two things follow.
Capacity replenishes as you build. Every month of production on Job B frees aggregate for the next pursuit. If you are near your limit, the question is not just "can I get more capacity" but "what is rolling off, and when."
Closing bonds out matters. A finished job that has never been formally closed out with the surety may still be sitting in your aggregate. This is real, common, and free to fix. See bond closeout and final premium.
Some sureties measure aggregate on total contract value rather than cost to complete, and some measure on remaining contract value rather than remaining cost. Ask which yours uses. On the numbers above, the three methods give $13.0M, $7.3M and roughly $8.4M — a difference big enough to change what you can bid.
Capacity is not just financial
The formulas set a ceiling. Four other things determine whether you get to it.
Experience with this type and size of work. A contractor who has completed twenty $500,000 jobs is not automatically qualified for one $10,000,000 job. Bigger jobs have different cash flow, different staffing, different owners and different consequences for error. Sureties want to see you step up in increments — roughly, they are comfortable with a job up to about twice your largest completed job, and get cautious beyond that.
Owner and contract quality. The same $8M job is a different risk for a well-funded public agency on a standard AIA contract than for a private developer on a heavily modified contract with onerous liquidated damages and no-damage-for-delay clauses. Sureties read the contract. Onerous terms consume capacity, or get declined outright.
Personnel. Who is running this job? Sureties want to see a project manager and a superintendent who have done work of this size. A large job with a first-time PM is a different application.
Track record and relationship. A ten-year account that has never had a claim, always delivers statements early, and hosts an annual meeting will get flexibility that the formulas do not describe. This is the least quantifiable and one of the most powerful factors, and it is entirely within your control.
The four ways to grow your line
1. Grow analyzed working capital
The dominant lever, because it is the multiplier on everything.
- Retain earnings. Every $100,000 left in the company is roughly $1,000,000 of single-job capacity. Weigh that against the distribution.
- Subordinate officer debt formally, in writing, on the surety's form. It moves from liabilities to net worth.
- Refinance short-term debt to long-term. Same debt, better bucket, immediate working capital improvement.
- Clean up the balance sheet before year end — related-party receivables, stale AR, inventory.
2. Fix what is being disallowed
Often faster than earning more. Ask your producer directly: what did the surety disallow on my last statement, and how much was it? Then fix the biggest item. A $275,000 affiliate receivable repaid before year end is $2.75M of single-job capacity for the cost of a wire transfer.
3. Build the relationship
- Statements within 90 days of year end
- Quarterly interims, unasked
- An annual meeting, in person, with the WIP and the plan
- Immediate disclosure of anything going wrong
4. Step up deliberately
Take the next job that is somewhat larger than your last, deliver it cleanly, and use it. Sureties raise limits on demonstrated performance more readily than on projected performance. A track record of five successive step-ups is more persuasive than any financial argument.
When to consider a second surety
Most contractors should be with one surety. Splitting your program dilutes the relationship, splits your financial story, and generally reduces total capacity rather than increasing it.
The genuine exceptions:
- You have outgrown your current surety's appetite for your size or trade
- You need capacity for a specialty your surety does not write
- Your surety's rating or ownership has changed in a way that concerns your customers
- You are being asked for capacity that would concentrate too much of one surety's exposure in one account
Move deliberately, with your producer, and expect the new relationship to start smaller than the one you are leaving.
Managing capacity day to day
Know your two numbers. Single limit and aggregate limit, and the expiration date.
Track consumption in real time. Cost to complete on every bonded job, updated at least monthly off the WIP.
Forecast forward. If you are pursuing three jobs and win all three, do you have room? Run that scenario before you bid, not after.
Chase closeouts. Every finished job that is still open in the surety's system is capacity you are paying for and not using.
Give notice on the big ones. Anything above your single limit needs two weeks minimum.
Use the bonding capacity calculator to run the numbers, and bonding capacity management for the relationship side.
The same capacity logic applies one tier down when you prequalify subcontractors. See Subcontractor Prequalification and the Subcontractor Risk Scorecard.
Not financial advice. Capacity multiples and measurement methods vary by surety. Confirm yours with your producer.
Try it: Bonding Capacity Calculator — single and aggregate capacity, current consumption, and how much room you have left to bid.