The Invoice Nobody Checks

1. The Invoice Nobody Checks

A builder running fifteen to forty subcontractors and suppliers receives their claims the same way every month. Some email a PDF. Some post a paper copy. Some text a total. The formats never match, the reference numbers rarely line up with the job, and the person responsible has to open each one and decide whether it is right.

Checking it properly means finding the purchase order or subcontract, comparing the rates, confirming the work claimed was actually done to that stage, checking whether a variation was ever approved, and confirming the cumulative total still sits inside the contract sum. Multiply that by thirty invoices. It is why so much of it happens on a Saturday.

This is not a niche problem, and the job market shows it. Large contractors and project consultancies advertise dedicated roles for exactly this work: Invoice Review Coordinator, Pay Application Coordinator, Contract Billings Coordinator. One such advertisement describes the duties as validating billed amounts against approved contracts, schedules of values, change orders and project progress, and ensuring every billed item is supported by documentation.

2. The Eight Things That Go Wrong

Almost every discrepancy on a subcontractor or supplier claim is one of eight things. None of them require bad faith; most are ordinary administrative drift.

The last one matters more than it looks. Paying an entity whose public liability or trade licence has lapsed can put the head contractor’s own cover at risk, and the check lives in a different folder from the invoice, so in practice it is the one most often skipped.

3. It’s a Control, Not a Task

The instinct is to treat invoice checking as a job to get through faster. It is better understood as a financial control, and controls are judged on different criteria: does it happen every time, does it happen the same way, and can you show afterwards that it happened?

A control that runs when someone remembers is not a control. Most small builders have no record of which invoices were checked against their agreements and which were simply paid, which means there is no way to tell a good month from a bad one, and no evidence to put in front of a subcontractor when a line is queried.

That reframing also decides what a useful tool looks like. The valuable output is not a clever answer. It is the same named checks, run on every invoice, with the working attached: the clause, the rate, the figure, the date it was checked.

4. “Can’t I Just Use ChatGPT?”

It is a fair question and it deserves a straight answer: for a one-off comparison, yes. Upload a PDF and a purchase order, ask what doesn’t match, and a capable model will do a decent job. Anyone technically confident can get value out of that today.

It falls apart as a monthly control, for four reasons that have nothing to do with how good the model is.

• 1.Finding the agreement is half the work. A chat tool has no purchase order register. Someone still has to locate the right PO, at the right revision, for the right job.
• 2.It has no memory of the job. Claiming ahead of progress and cumulative overruns can only be detected against what was already claimed and paid on previous invoices.
• 3.It leaves no record. A chat transcript is not a workpaper. There is nothing to show that an invoice was checked, or what it was checked against.
• 4.It relies on the operator every time. The person doing accounts has to remember, upload the right files, and phrase the question the same way as last month. Two runs can disagree, which is a real problem for a control.

There is a governance point too. Subcontract pricing and rates are among the most commercially sensitive documents a builder holds, and plenty of businesses have (or should have) a policy about pasting them into a consumer chat tool.

5. What an Automated Check Looks Like

The useful version is deliberately boring: a fixed sequence with fixed rules, that slots into the process a builder already runs. No new project management system, no portal for subcontractors to log into, no change to how invoices arrive.

1. 1

   Intake

   Invoices are forwarded to an address, or picked up from the inbox they already arrive in. Nothing changes for the subcontractor.

2. 2

   Match

   The claim is tied back to the right purchase order, subcontract or scope for that job, and to everything previously claimed against it.

3. 3

   Run the named checks

   The eight checks in section 2, every time, in the same order. No prompt to write, no judgement asked of the operator.

4. 4

   Produce the working

   One page per invoice: nothing to flag, or a short list of what doesn’t match, each item pointing at the clause or line it conflicts with, with the dollar figure.

5. 5

   Keep the record

   Dated, per invoice, per job. This is the part that turns a task into a control, and the part a chat window cannot give you.

6. What It’s Worth

Nobody publishes a reliable error rate for Australian subcontractor claims, and we are not going to invent one. What is published sits in an adjacent field: in freight and parcel invoicing, audit specialists put the share of invoices carrying some kind of error at 5 to 10 per cent, and organisations without a systematic check are estimated to lose 3 to 5 per cent of spend to billing errors. Different industry, same mechanics: many small line items, unstructured documents, and no one comparing them to the agreement.

The honest way to size it for your own business is to take one month of subcontractor claims and check them properly. Contractors who do this typically find a handful of small discrepancies rather than one large fraud: a rate that drifted, a variation that was never signed, an item claimed twice.

On the cost side, the existing options are priced for a different business. Procurement platforms with automated three-way matching generally start in the low hundreds of dollars a month and run to $850 and beyond, and they assume a structured purchase-order process already in place. The specialist construction payment platforms are aimed at projects in the hundreds of millions. Between those and a spreadsheet, there is not much.

7. Where to Start

You do not need software to get most of the way. Four steps, in order.

1. 1

   One inbox for claims

   A single address every subcontractor and supplier must send to. Nothing else on this list works until invoices stop arriving by text.

2. 2

   A purchase order for every engagement

   With the agreed value, the scope, and the quote attached. An invoice can only be checked against something; the PO is that something.

3. 3

   Check one month by hand, and write down what you find

   Use the eight checks in section 2. The list of what you found is the business case, and it costs you one afternoon.

4. 4

   Only then automate

   If the month you checked by hand turned up nothing, you have saved yourself buying software. If it turned up a pattern, you now know exactly which checks to automate first.