price-check

---
name: price-check
description: Compares a supplier's invoices against the price you agreed, line by line, and produces the list of lines to challenge with the money attached.
---

# Find out exactly what your supplier overcharged you, and how much to ask back

You give this the invoices from one supplier, whatever you have in writing about the prices you agreed, and the delivery notes. It gives you back a list of the lines where the charge does not match the agreement, each with the pounds and pence attached, sorted biggest first, in wording you can send to your account manager. It never guesses at a price you cannot evidence.

## What it does

1. **Pin down one supplier, one period, and three piles of paper before anything else.** Take the invoices for a single supplier across a stated date range, the written agreement on prices (a signed price list, a tender response, an order confirmation, or the email where the rep set out the rates), and the delivery notes or goods received notes for those same deliveries. Write the supplier name, your account number and the exact date range at the top of the output, because a challenge that covers a vague period gets bounced. If there is nothing in writing about prices at all, say so in one line and use the last invoice before the period as the comparison baseline, clearly labelled as "last invoice price, not an agreed price".

2. **Type every invoice line into one table before comparing a single figure.** The columns are: invoice number, invoice date, delivery note number, supplier product code, description, pack size as printed (for example 6 x 2kg, 12 x 1L, 1 x 5kg), quantity charged, unit of measure, unit price excluding VAT, line total excluding VAT, VAT rate. A full VAT invoice must already carry most of this: HMRC's guidance at VATREC5010 requires "the quantity of the goods or the extent of the services" and "the unit price". If a line does not show a unit price or a quantity, record it as its own finding, because you cannot check a price that the supplier has not shown you.

3. **Convert every line to a price per base unit before you compare anything.** Base units are per kilogram, per litre, or per single item, never per case. A 6 x 2kg case at £54.00 is £4.50 per kg; a 6 x 1.8kg case at £52.00 looks cheaper per case and is £4.81 per kg. Pack sizes change between order cycles while the case price stays still, so a comparison of case prices will miss the increase entirely. Show both the case figure and the per-base-unit figure in the table so the owner can see the conversion.

4. **Match invoice lines to the agreed price on the product code first, and never on description alone.** Supplier product codes are the only stable key; descriptions get shortened, reworded and reused across different packs. Where the code on the invoice does not appear on the agreed price list, do not force a match to something that sounds similar. Put those lines in a separate list headed "no agreed price found for this code", and keep them out of the money total for the rest of the run.

5. **Compare charged price against agreed price per base unit, and name the cause of each gap.** Flag every difference of one penny or more per base unit; a contract price has no rounding tolerance. Classify each one as a rate that has drifted above the agreed list, a price from a superseded week, or an increase the supplier applied without the notice your contract requires. Supy's analysis of restaurant invoices names quantity discrepancies and prior-week rate charging as "the two most common overcharge mechanisms", describing the second as where a "supplier invoices at last week's price rather than the current agreed rate". On the notice point, the UK hospitality supplier guide from Jelly is blunt: "without an express contractual mechanism a supplier is not entitled to vary price unilaterally", so an uplift with no contractual mechanism behind it belongs on the challenge list, not in your food cost.

6. **Check quantity against the delivery note, not against the invoice.** The invoice is the supplier's account of what they sent; the delivery note signed in your kitchen is the record of what arrived. Compare them line by line and flag any case, kilo or litre charged that the delivery note does not show, and any line where someone wrote a shortage or refusal on the note and no credit note followed. Where a delivery note is missing for an invoice, say "no delivery note held" against that invoice rather than assuming the quantity was right.

7. **Test every line marked market price, MP, or daily quote separately.** These are usually fresh produce, fish and meat, and they sit outside the fixed list on purpose. For each one, ask for the quote sheet or price email for that delivery week and compare against it. If no quote sheet exists for that week, the line has no agreed price and cannot be challenged on price alone; list it as "market price, no quote sheet held" and tell the owner to ask the supplier to send the weekly sheet from now on.

8. **Take cost-plus and rebate arrangements apart into the cost and the plus.** If you buy on cost plus a percentage, check both halves: that the mark-up percentage on the invoice is the one you agreed, and that the underlying cost figure is evidenced by something you can see. The cost side is the half nobody checks, and it is the half that was litigated in the U.S. Foodservice cost-plus class action decided by the Second Circuit on 30 August 2013, where the "cost" the customers were billed on was alleged to have been inflated through intermediary companies before it ever reached the invoice. Do the same for rebates and volume discounts: work out what the agreed rate should have produced for the period's spend, compare it to what was actually credited, and list any shortfall as its own line.

9. **Write the challenge list sorted by money, with the sentence to send underneath it.** Each row carries: invoice number, invoice date, product code, description, price charged per base unit, price agreed per base unit, difference per unit, quantity, total overcharge in pounds, and the name and date of the document the agreed price came from. Total the column, then write a short request for a credit note quoting the invoice numbers and the total, with no adjectives and no accusation. Keep three lists separate and clearly headed: challenge these, no agreed price found, and price rises that appear to be contractually valid, because sending the third group as a claim is how the first two get ignored.

## Then it checks

1. Every row on the challenge list shows an invoice number, an invoice date, a product code, a price charged, a price agreed and a total in pounds and pence, with no row reading "approx", "circa" or "tbc".
2. Every agreed price in the output names the document it came from and that document's date, and no agreed price is sourced from a previous invoice unless that row is labelled "last invoice price, not an agreed price".
3. Every price comparison is expressed per kilogram, per litre or per item, with the same unit on both sides of the comparison, and no row compares a case price to a weight price.
4. The stated total equals the sum of the individual line totals when added up, and the arithmetic on each row (difference per unit multiplied by quantity) reproduces that row's total.
5. Lines with no agreed price to compare against appear only in the "no agreed price found" list and contribute nothing to the challenge total.
6. Every market-price and cost-plus line either names the quote sheet or cost document it was checked against, or appears as "unverifiable, ask the supplier for the figures".

Any check fails: name it, redo that step once. Failed twice: say what is wrong and stop.

## Rules
- Public information only.
- Never invent a fact, a number or a quote.
- Never fill a missing agreed price with an estimate, a competitor's website price, or a figure from another supplier. One made-up number in a claim gives the supplier grounds to dismiss the whole list, including the overcharges that are real.
- Never smooth a pack-size conversion to make two lines comparable. If the invoice does not state the pack size, say the line cannot be checked rather than assuming the pack you usually buy, because a claim built on the wrong pack size is a claim the supplier can prove wrong.
- Never present a price rise that the contract permitted as an overcharge, and never present a suspicion as a finding. Mixing a valid increase into a credit request costs the owner the goodwill of the account manager who has to approve the genuine credits.
- This output is a working document prepared for the owner's accountant or solicitor to check before any money is claimed or withheld. It reads invoices and states arithmetic; it is not legal advice on your supply contract, and nothing in it should be treated as a ruling on what the contract entitles you to.

## Built from
- Supy, "Supplier Overcharging Restaurants: How Undetected Invoice Errors Drain Food Cost Margin", https://supy.io/blog/learn-supplier-overcharging-restaurants, 20 June 2026: the three failure shapes the comparison sorts gaps into, and the finding that quantity discrepancies and prior-week rates are the two most common, which is why step 6 checks the delivery note separately.
- Dana Moran, "Analysis: 35% of college food invoices have overcharges", FoodService Director, https://www.foodservicedirector.com/colleges-universities/analysis-35-of-college-food-invoices-have-overcharges, 22 February 2016: the scale that justifies checking every line rather than spot-checking, and the observation that a typical overcharge is a small percentage of a large invoice, which set the one-penny-per-base-unit flag threshold.
- HM Revenue & Customs, "VATREC5010 - VAT invoice: Details which must be shown on a full VAT invoice", https://www.gov.uk/hmrc-internal-manuals/vat-trader-records/vatrec5010, last updated 16 January 2025: the column list in step 2, and the basis for treating a missing unit price or quantity as a finding in its own right.
- Jelly, "Supplier Price Fluctuation Management for UK Hospitality", https://blog.getjelly.co.uk/supplier-price-fluctuation-management-uk/, 25 August 2026, updated 4 September 2026: the UK position that a supplier cannot vary price unilaterally without a contractual mechanism, and that notice periods come from the contract rather than from statute, which is what separates a challengeable uplift from a valid one.
- FindLaw, "In re: U.S. Foodservice Inc. Pricing Litigation", United States Court of Appeals for the Second Circuit, https://caselaw.findlaw.com/court/us-2nd-circuit/1642931.html, decided 30 August 2013: the reason step 8 checks the cost half of a cost-plus deal as well as the mark-up.

# price-check

## You are given
A folder from a UK hospitality business covering one supplier and one stated date range: the invoices (PDF, photograph or CSV), whatever is in writing about the prices agreed (a signed price list, a tender response, an order confirmation, or the email where the rep set out the rates), the delivery notes or goods received notes for those same deliveries, any weekly quote sheets for market-price lines, and any rebate or cost-plus agreement. The supplier name, account number and date range are supplied in a text file. Assume pack sizes are printed inconsistently, descriptions have been reworded between invoices, and some invoices have no matching delivery note.

## Produce
Write into an `output/` folder next to the inputs:

1. `invoice-lines.csv` with these columns in this order: `Invoice number`, `Invoice date`, `Delivery note number`, `Supplier product code`, `Description`, `Pack size as printed`, `Quantity charged`, `Unit of measure`, `Unit price excluding VAT (GBP)`, `Line total excluding VAT (GBP)`, `VAT rate`, `Price per base unit excluding VAT (GBP)`, `Base unit` (kg, litre or item), `Source file`. Every line on every invoice in the range appears here once.
2. `challenge-list.csv` with these columns in this order: `Invoice number`, `Invoice date`, `Supplier product code`, `Description`, `Price charged per base unit excluding VAT (GBP)`, `Price agreed per base unit excluding VAT (GBP)`, `Difference per base unit (GBP)`, `Quantity`, `Base unit`, `Total overcharge (GBP)`, `Agreed price document`, `Document date`, `Cause`. `Cause` holds exactly one of: `rate above the agreed list`, `price from a superseded week`, `increase applied without the notice the contract requires`. Sorted by `Total overcharge (GBP)`, highest first, with the column total at the foot.
3. `no-agreed-price.csv` with columns: `Invoice number`, `Invoice date`, `Supplier product code`, `Description`, `Pack size as printed`, `Price charged per base unit excluding VAT (GBP)`, `What was searched for`, `Nearest code on the agreed list`. These rows contribute nothing to the challenge total.
4. `valid-increases.csv` with columns: `Invoice number`, `Invoice date`, `Supplier product code`, `Description`, `Old price per base unit excluding VAT (GBP)`, `New price per base unit excluding VAT (GBP)`, `Difference per base unit (GBP)`, `Clause or notice that permits it`, `Document and date`. Sent to nobody as a claim.
5. `quantity-differences.csv` with columns: `Invoice number`, `Invoice date`, `Delivery note number`, `Supplier product code`, `Description`, `Quantity on the invoice`, `Quantity on the delivery note`, `Difference`, `Unit price excluding VAT (GBP)`, `Value of the difference (GBP)`, `Shortage written on the note` (yes/no), `Credit note raised` (number, or `none`). Where no delivery note is held for an invoice, the row reads `no delivery note held` and the quantity is not assumed correct.
6. `market-price-lines.csv` with columns: `Invoice number`, `Invoice date`, `Supplier product code`, `Description`, `Price charged per base unit excluding VAT (GBP)`, `Quote sheet for that week` (file name, or `no quote sheet held`), `Quoted price per base unit excluding VAT (GBP)`, `Difference per base unit (GBP)`, `Checkable` (yes/no).
7. `cost-plus-and-rebates.csv` with columns: `Arrangement`, `Agreed mark-up %`, `Mark-up % on the invoice`, `Underlying cost figure charged (GBP)`, `Document evidencing that cost`, `Agreed rebate rate`, `Spend in the period net of VAT (GBP)`, `Rebate the rate should have produced (GBP)`, `Rebate actually credited (GBP)`, `Shortfall (GBP)`, `Verifiable` (yes / `unverifiable, ask the supplier for the figures`).
8. `challenge-email.md` - subject line: the account number, the date range and the words `price query`. Body: one short paragraph, the challenge table, the total in pounds and pence, and a request for a credit note quoting the invoice numbers and the total. No adjectives and no accusation. The three lists stay separate and clearly headed; only the challenge list is sent.
9. `conversions.csv` with columns: `Supplier product code`, `Pack size as printed`, `How it was read`, `Units in the pack`, `Base unit`, `Case price excluding VAT (GBP)`, `Price per base unit excluding VAT (GBP)`. One row per distinct pack size seen, so the conversion can be checked.
10. `README.md` - the supplier name, the account number, the exact date range, the files read, the number of invoice lines, the number challenged, the challenge total, and whether an agreed price document was held or the last invoice before the period was used as the baseline.

## Rules
- Match on the supplier's product code first, and never on description alone. A code on the invoice that does not appear on the agreed price list goes to `no-agreed-price.csv`. Never force a match to something that sounds similar.
- Convert every line to a price per kilogram, per litre or per single item before comparing anything. Never compare a case price to a case price, and never compare a case price to a weight price.
- Never smooth a pack-size conversion. If the invoice does not state the pack size, the line cannot be checked; put it in `no-agreed-price.csv` with `pack size not stated` in the search column.
- Flag every difference of one penny or more per base unit. A contract price has no rounding tolerance.
- Never fill a missing agreed price with an estimate, a web price, a competitor's price or a figure from another supplier. Where there is nothing in writing about prices at all, use the last invoice before the period as the baseline and label every affected row `last invoice price, not an agreed price`.
- Never put a price rise the contract permitted into the challenge list. It goes in `valid-increases.csv` and is not sent.
- Check quantity against the delivery note, never against the invoice. A missing delivery note is recorded, not assumed away.
- All prices go in excluding VAT and are labelled as such. The stated challenge total must equal the sum of the line totals, and difference per unit multiplied by quantity must reproduce each row's total exactly.
- No cell may read `approx`, `circa` or `tbc`.
- Round only at the point of display, to two decimal places.
- Use British English, £, and DD Month YYYY dates. No em dashes.
- The output is a working document prepared for the owner's accountant or solicitor to check before any money is claimed or withheld. Write no sentence about what the contract entitles anyone to.

## Return
A list of the files written with their absolute paths, the number of invoice lines read, the number on the challenge list, the challenge total in pounds and pence, the number in `no-agreed-price.csv`, the number of market-price lines with no quote sheet, and whether the baseline was an agreed price document or the last invoice before the period.