What is underbilling?
Underbilling is when the cost you have incurred on a job exceeds what you have billed for it. It appears on a work in progress schedule as costs in excess of billings, and it represents work you have already paid for but not yet invoiced.
Why it happens
Some underbilling is normal and unavoidable. You perform work in the first week of the month and invoice at the end of it, so at any given moment there is always work done and not yet billed. That resolves itself on the next cycle.
The kind that matters does not resolve. It usually comes from one of three places:
Unapproved change orders. You performed work under a change order nobody has signed. The cost lands on the job, the contract value has not officially grown, and the difference sits as underbilling until somebody approves it.
A billing cycle that lags the field. Paperwork moves slower than crews do. This is a back-office capacity problem and it shows up as a balance that never quite clears.
Cost overruns not yet recognized. The job is costing more than estimated and the schedule of values has not been revisited.
The three have completely different fixes, which is why splitting the balance is the first useful thing to do with it.
How much is normal
There is no single correct figure, but surety and construction accounting guidance points at two ratios where underwriters start asking questions:
| Measure | Concern threshold |
|---|---|
| Underbillings as a share of working capital | 20 to 25% |
| Underbillings as a share of active contract value | 10 to 15% |
Context matters more than the ratio. A contractor with a strong balance sheet and a decade of clean closeouts gets more latitude than one without.
Why it is watched so closely
Underbilling is one of the first lines a bonding agent, surety underwriter or bank looks at, because a large balance has two possible explanations and neither is reassuring. Either the back office cannot keep pace with the field, or significant work has been performed without a signed agreement. Both read as cash flow risk.
It is also a leading indicator. Underbilling built on unapproved change orders often converts to written-off revenue at job close, which is where it becomes profit fade and starts damaging the credibility of every schedule you submit afterwards.
Going deeper: How unapproved change orders quietly cap your bonding capacity