Teardown: what an audit of $1.26M in materials invoices actually found

Most invoice-audit marketing quotes a recovery percentage and moves on. This is the opposite: one real audit, anonymized, with every number that came out of it — including the ones that make the case weaker. Three months of materials invoices from a single distributor, run through GuardianPrice against the contracted price lists in effect on each invoice date.

The scope

• 3,589 invoice lines across 875 invoices, May through July.
• $1,263,951 of invoiced materials spend.
• One distributor, several price lists with overlapping effective dates.
• No sampling — every line was matched, or explained why it could not be.

What it found

206 lines were billed above the contracted price in effect that day, totalling $14,896 in overcharges. Spread across $1.26M of spend that is roughly 1.2% — small enough that nobody would ever notice it on an invoice, large enough to be real money at the end of a year. The average overcharge was under 1% of the line; the worst single line was 51% over contract.

The audit also surfaced $25,619 of undercharges. That number matters. A tool that only reports overcharges is selling you a one-sided view of your own data, and a supplier who finds out you were quiet about the other direction will use it. The honest framing is a net position, then a claim built only on the overcharged lines you can evidence.

The overcharges clustered, they did not scatter

The 206 overcharged lines came from just 83 distinct SKUs. That is the single most useful finding in the whole audit: this was not random error, it was a handful of items priced off a stale list and then repeated on every order for three months. Fixing 83 SKUs at the source removes almost all of the future leakage — which is worth more than the $14,896 already lost.

The uncomfortable part: 1,751 unmatched lines

Nearly half the lines could not be matched to a contracted price at all. This is where most audit tools stop and report a number. Broken out by reason, it stops being a failure and becomes a work list:

• 1,092 — no product family match. The SKU did not stem to anything on a price list. Overwhelmingly catalogue items bought outside the contracted range.
• 308 — non-material lines. Freight, surcharges, deposits. Correctly excluded; these were never going to match a product price list.
• 212 — SKU missing from every loaded price list. A coverage gap, not a supplier error.
• 129 — a family match was suggested but not confident enough to auto-apply. These are the highest-value review queue in the audit.
• 10 — no-charge lines.

Read that list and the priority is obvious. Roughly 9% of lines are one confident review pass away from being audited, and another 6% need price-list coverage the buyer simply never loaded. The remaining bulk is off-contract purchasing — a procurement question, not an audit one.

What we would tell this buyer to do next

• Claim the $14,896 with line-level evidence: invoice, date, contracted price, delta. It is a five-minute conversation when the evidence is per line.
• Send the 83 SKUs to the distributor as a price-file correction, not as a dispute. That is where the recurring money is.
• Load price lists for the 212 uncovered SKUs before the next cycle so those lines audit themselves next month.
• Work the 129 suggested-family lines once by hand; each confirmed alias permanently audits that SKU going forward.
• Leave the undercharges alone, but know they exist before the renewal conversation.

The honest conclusion

One point two percent leakage on a single distributor over one quarter, found without sampling and with every unmatched line accounted for. If your materials spend looks like this one, the recovery pays for the software several times over — but the durable value is the 83-SKU fix and the coverage gaps, not the cheque.