The Valuation Is Not a Timesheet
A contractor bills measured work against a bill of quantities, less retention, on a certificate. A project system bills hours times a rate. Both are called invoicing and they are not the same instrument — here is what each does, and how to run one alongside the other honestly.
Ask a quantity surveyor what a project invoice is and you get a precise answer: a valuation of work measured on site against the priced bill, gross to date, less what was previously certified, less retention, less any contra charges, certified by somebody with the authority to certify it.
Ask a project management system the same thing and you get a different precise answer: hours logged, multiplied by a rate, on an invoice to a customer.
Both are correct. They describe different commercial arrangements, and the trouble arrives when a contractor assumes a system that can do the second can do the first. It cannot, and the distance between them is not a configuration setting.
Two ways to get paid for building something
Almost every construction contract sits in one of these camps, or moves between them for different portions of the work.
Measured work
- Priced against a bill of quantities agreed at tender.
- Valued by measuring what was built, not by counting effort.
- Certified — a third party confirms the measure before payment is due.
- Cumulative: gross to date, less previously certified.
- Retention held back and released after defects liability.
Time and materials
- Priced at agreed rates per hour or per day.
- Valued by counting effort actually expended.
- Invoiced directly, usually without a certifier.
- Periodic: this period's hours, billed once.
- Rarely any retention.
The second column describes a genuinely common arrangement in construction — dayworks, variations instructed without an agreed rate, small works orders, consultancy, and much of the fit-out and maintenance market. It is not a lesser arrangement. It is simply a different one, and it is the one a project system bills.
A valuation measures what was built. A timesheet counts what was spent. On a good job those two numbers are related, and on no job are they the same.
What the project invoicing actually does
It is worth describing precisely, because it does its own job well and the controls in it are the kind that matter.
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It requires a customer on the project
No customer, no invoice — it refuses rather than producing something addressed to nobody.
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It takes billable, uninvoiced time that has a rate
Three conditions, each of which excludes work silently if it is not met. Time marked non-billable is out, time already invoiced is out, and time with no rate against it is out.
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It uses the rate that applied to the entry
Each time entry carries its own rate snapshot, falling back to the project default. So raising your rates next month does not retroactively reprice work logged last month, which is the behaviour you want and not the behaviour you always get.
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It groups into one line per rate
Rather than one line per entry, which would produce an invoice nobody reads. Different rates become different lines, which is also how a client wants to see it.
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It stamps every entry with the invoice
This is the important control. Each billed entry records which invoice took it, so the same hour cannot be billed twice — not by accident, not by running the process again, and not by a second person doing it in parallel.
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It produces a draft
Not an issued invoice. Somebody reads it, adjusts it and sends it, which is where a rate that looks wrong or a period that looks light gets caught.
The silent exclusion worth checking first
Time with no bill rate is skipped rather than billed at zero or flagged. If your first invoice from a project looks light, the likely cause is entries logged before a rate was set, or logged by someone whose rate was never configured. Check the total hours logged for the period against the hours that appeared on the invoice before you go looking for anything more complicated.
What AWRA OpsHub does today
- Draft customer invoices built from billable, uninvoiced logged time, grouped into one line per rate.
- A per-entry rate snapshot, so a rate change does not retroactively reprice work already logged.
- Double-billing is prevented structurally — every billed entry is stamped with the invoice that took it.
- Guarded by an invoicing permission, so raising client invoices is a distinct capability rather than something anyone with project access can do.
- It produces a draft, so a person reviews the figure before a client ever sees it.
What it does not do
- No bill of quantities. There is no priced bill, no measured-work valuation and no percentage-complete billing against a rate schedule. This bills hours.
- No retention. Nothing withholds a percentage, tracks what is being held, or releases it after defects liability. If your contract retains, that is a deduction you manage outside this.
- No cumulative certificate structure. Invoices are periodic rather than gross-to-date-less-previously-certified, so a valuation series cannot be reconstructed from them.
- No certifier. There is no role that approves a valuation before it becomes payable, and no record of a certificate number or date.
- Time with no bill rate is skipped silently, so an invoice can come out light with nothing indicating why.
Not ours, by choice
- We will not call a time-and-materials invoice a valuation. A contractor on a measured contract who took this for a certificate would be building a commercial position on the wrong instrument, and that is a much more expensive mistake than a missing feature.
- We will not invent a percentage complete. Billing a proportion of a bill line because a task is marked eighty per cent done would be manufacturing a valuation from a status field, and no quantity surveyor would accept it — nor should they.
A bill of quantities with measured-work valuations, cumulative certificates and retention held as a receivable is a substantial and well-understood build rather than a ceiling. The customer invoice model, the project cost side and the Payments Register integration all exist; the contract side would be specified against your standard form and priced accordingly.
The split to be clear about before buying is the one already set out in the construction ERP guide: the materials, plant and buying side is real, and the contract side — bill of quantities, variations, retention, certificates — is not here. A contractor who needs both should expect to run this alongside a measurement package rather than instead of one.
Running both without lying to yourself
Most contractors with any scale have both kinds of work running at once — a main contract on measured valuations, and dayworks, small orders and variations billed on time. The practical question is how to keep the two straight.
Keeping the two streams honest
- Decide, per project, which arrangement it is. A project billed on measured work should not have billable time logged against it, or somebody will eventually invoice it twice.
- For measured contracts, use the project for cost and the measurement package for value. Cost-to-date here, valuation there, and compare them deliberately rather than letting one imply the other.
- For dayworks under a measured contract, consider a separate project. It keeps the billable time cleanly separated from the contract cost and makes the daywork invoice a self-contained thing.
- Never treat cost-to-date as a valuation. They differ by your margin, by unbilled measured work, and by whatever has been done and not yet certified — three quantities that move independently.
- If you retain, deduct it on the invoice as a line and track what is held somewhere you will actually look. Nothing here does that for you, and retention forgotten is the most common unclaimed money in the industry.
- Reconcile the hours logged against the hours billed each month. The gap is entries with no rate, entries marked non-billable, and entries somebody forgot to mark billable at all.
The fourth item is worth stating firmly because the mistake is so easy to make and so hard to unwind. Cost-to-date is a fact about what you have spent. A valuation is an assertion about what you have earned, and a client's representative has to agree with it. Presenting one as the other in a management report produces a profit figure that changes when somebody measures the site.
What the time record is worth even on a measured contract
It would be easy to conclude that a contractor on measured valuations has no use for time logging. The opposite is true, and it is the reason to keep it accurate even where it bills nothing.
Logged time against tasks is what tells you the cost side of a valuation. When a bill item is measured and certified at a value, the useful question is what it cost to produce, and that answer is labour hours plus materials issued plus plant. Without the hours, the cost side is an allocation and the margin on any individual item is a guess.
It is also what makes the next tender better. A contractor who knows how many hours the same operation took across four jobs prices the fifth from evidence, and one who does not prices it from the last argument about it.
The cost comparison itself is in BQ versus actuals, the labour payment side in paid for the hours the site logged, and the certificate discipline for subcontractors in subcontractors and certificates.
Our take
If your work is billed on time — dayworks, small orders, fit-out, maintenance, instructed variations without an agreed rate — the invoicing here does that job properly, and the double-billing control is the part worth having, because time billed twice is discovered by a client rather than by you. If your work is billed on measured valuations against a bill of quantities, this is not that instrument and no setting turns it into one: there is no bill, no certificate, no retention. Run it for cost and run measurement separately, and never let cost-to-date stand in for a valuation in a management report.
See time turned into a draft invoice
Billable uninvoiced hours at the rate that applied when they were logged, grouped one line per rate, every entry stamped so nothing bills twice, and a draft a person reviews before a client sees it.
Explore project billingFrequently asked questions
Can we produce interim valuations against a bill of quantities?
No. There is no priced bill, no measured-work valuation, no percentage-complete billing against a rate schedule, and no certificate structure of gross-to-date less previously certified. What exists bills logged hours at a rate. If your main contract runs on measured valuations, you should expect to run a measurement package alongside this rather than instead of one, and use the project for the cost side.
Does it handle retention?
No. Nothing withholds a percentage, tracks what is being held, or releases it after defects liability. If your contract retains, deduct it as a line on the invoice and track the held balance somewhere you will actually look at it. Worth saying firmly because forgotten retention is among the most common unclaimed money in the industry — it is real revenue you have earned, and it tends to live in one person's memory rather than in any system.
Can the same hours be billed twice?
No, and this is the control worth having. Every time entry that goes onto an invoice is stamped with that invoice, so it cannot be picked up again — not by running the process a second time, not by a colleague doing it in parallel, and not by accident at a period boundary. Time billed twice is the kind of error a client discovers rather than you, which makes it disproportionately expensive relative to its size.
Our first project invoice came out lighter than expected. Why?
Almost always one of three silent exclusions. Time marked non-billable is skipped, time already invoiced is skipped, and — most commonly on a first invoice — time with no bill rate against it is skipped rather than billed at zero or flagged. That last one catches entries logged before a rate was set or by someone whose rate was never configured. Compare total hours logged for the period against hours that appeared on the invoice; the gap will point straight at it.
If our rates go up, does old unbilled time reprice?
No. Each time entry carries the rate that applied when it was logged, falling back to the project default, so raising rates next month does not retroactively reprice work logged last month. That is the behaviour you want and it is not universal — it means a client cannot be presented with an invoice for old work at a new rate, and it means your unbilled work in progress is valued at what you actually agreed at the time.
Is logging time worth it if we bill on measured work?
Yes, for two reasons that have nothing to do with invoicing. It gives you the cost side of a valuation — when a bill item is certified at a value, what it cost to produce is labour hours plus materials plus plant, and without the hours the margin on any individual item is a guess. And it makes the next tender better: a contractor who knows how many hours an operation took across four jobs prices the fifth from evidence rather than from the last argument about it.
