A billing error is measured against the margin, not against the invoice

21 September 2026 · Šis puslapis pateikiamas anglų kalba.

Kristel Mägi

An overcharge is small against the invoice it sits on and large against the margin it comes out of. In wholesaling the gross operating surplus is under six cents in the euro of turnover, so two per cent on the goods takes a visible share of the year.

That ratio is the argument behind Price Double Check: an invoice and the price list, forwarded by email, come back as the lines where the two do not agree. What follows is the sum done properly — what the published figures say a distributor keeps out of a delivery, and what one line of one real invoice took out of it.

The denominator is the margin, not the invoice

Most buyers read a difference against the document it appeared on. Four hundred euros on a twenty-thousand-euro delivery is two per cent, and two per cent sounds like the noise any month contains. The number that decides whether it matters is not the twenty thousand. It is what the business keeps out of the twenty thousand, and in wholesaling and retailing it keeps very little.

Eurostat puts the gross operating rate of the EU distributive trades — gross operating surplus, which is value added less personnel costs, set against turnover — at 5.8% in 2023, the lowest of any section of the business economy. That is before depreciation, interest and tax, so what reaches the bottom of the accounts is smaller again.

Hold that rate steady and assume purchases run at eighty per cent of turnover, which is roughly where a distributor of other people's brands sits. On a million euros of purchases, here is what an overcharge on the goods is worth against the surplus those goods helped produce.

The table makes two assumptions and states both: the sector operating rate above, and purchases at eighty per cent of turnover. Move either and the figures move with them. The shape does not move. A single percentage point added on the cost side arrives in the margin at nearly fourteen times its size, which is the reason a difference worth arguing about on the invoice is rarely worth ignoring.

What one real line did

The documents behind this service are a real chain: a sports-nutrition manufacturer in Spain, a Baltic distributor beneath it, and a small buyer beneath that. Eleven invoices in scope, 382 invoice lines, every one of the eleven reconciled to its own printed total to the cent before anything was compared. Forty-one lines carried a genuine price difference. One of them carried most of the damage.

Item 5046 was billed at €13.23 against €11.235 in the last price list the buyer had been sent: 17.75% on the unit, €47.76 on that invoice. Next to the delivery it sat in, €47.76 is a rounding error. Against the margin that delivery produced it was 91%. The reason it went unnoticed for a year is duller than fraud. The current year's list was never sent at all, and a price compared against nothing looks fine.

The small ones are the ones that last

A single large overcharge is the rare case. The expensive pattern is the difference too small to fight over, repeated every month, and three of them sat in the same set.

• A substitution nobody announced: a 550cc item at €2.07 replaced by an 800ml item at €2.59 under a different code, €15.60 across the set. No line was billed incorrectly. The line that should have been billed was the one that disappeared.
• A price that became the new normal: a bar invoiced at €1.26 from March while the list in force said €1.176. The list caught up in October. Every invoice in between was wrong in the same small way, and each one alone was arguable.
• Four pack sizes that shrank at an unchanged price. Invoices do not print pack sizes, so nothing on the invoice moved at all. The two price lists side by side show it, and nothing else does.

A one-off costs once. A new normal costs every month until somebody compares two documents that were never meant to be read together, which is why the year matters more than the invoice and why a check that runs on ordinary months beats a check that runs on suspicious ones.

The honest half of the arithmetic

Counting every difference as money owed back is how a control loses its audience. Price lists carry four decimals and invoices carry two, so a cent per unit is rounding rather than a finding; half-up at the line, with a tolerance of one cent, is what keeps a routine from crying wolf. Freight has no reference price anywhere, and the same set held seven freight lines worth €901.65 that no document can judge. Six items appeared on invoices and in no list at all, which is an absence of basis, not an overcharge. Strip those out before multiplying anything by fourteen.

What is left after the honest deductions is still worth the hour: 41 lines out of 382, each one a price the buyer had been given in writing and was not billed at. The method those figures came from is set out in how to check an invoice against a price list, and the letter that turns a finding into a credit note is a separate short piece.

Forward one invoice and the price list it should have been billed on, and the comparison comes back by email: the lines that differ, the price on each side and what the difference is worth. The prices are on the home page.