In this article, learn about:
- What the GCA's 2026 annual survey reveals about compliance failures across UK grocery retailers
- Which issues are getting worse for suppliers and which retailers are falling short
- How invoice accuracy and electronic documentation connect to commercial disputes
- What to fix before Golden Quarter order volumes make every error more expensive
The 2026 Numbers
The Groceries Code Adjudicator's 2026 annual supplier survey gathered responses from more than 2,600 UK suppliers. Published in April and discussed at the GCA's annual conference on 29 September, the results show overall compliance remaining high across the 14 designated retailers. They also show the areas where suppliers are consistently losing ground.
| Issue | % of suppliers affected (2025) | % of suppliers affected (2026) |
|---|---|---|
| Inadequate invoice discrepancy resolution | 17% | 20% |
| Significant costs from inaccurate retailer forecasting | 17% | 18% |
| Refusal or delays in agreeing cost price increases | 14% | 15% |
| Delays in payments | 11% | 14% |
Invoice discrepancies are the most common problem suppliers report. Late payments saw the largest proportional increase year on year. Both are areas where the quality of electronic trading documentation makes a direct difference to the outcome.
Why Invoice Discrepancies Lead the List
An invoice discrepancy happens when a buyer's purchase order, the advance despatch notification, and the invoice do not agree. A quantity difference between what was ordered and what arrived. A price that does not match the agreed terms. A line item on the invoice that does not correspond to the DESADV the retailer received. Each of these creates a resolution process.
That process takes time. In many cases it takes weeks. The deduction sits on the account while it runs, affecting cash flow even when a supplier is ultimately found to be correct.
Three things make invoice discrepancies more likely:
- Manual invoice processing
Invoices that are created manually rather than generated from a confirmed order are more likely to carry transcription errors. Those errors are easier to miss before the invoice is sent and harder to resolve once a retailer has raised a dispute. - Mismatches between the DESADV and what arrives
If the advance despatch notification says one quantity and the physical delivery is different, the retailer's system flags a discrepancy automatically. The cause is often a last-minute change that was not reflected in the electronic document before it was sent. - Missing or incorrect line-level data
Product codes, trade unit quantities, and invoice line references all need to match across documents. A single incorrect field can cause an automatic rejection in a retailer's accounts payable system and trigger a manual review queue rather than a straight-through payment.
Cost Price Increases and the Evidence Problem
The percentage of suppliers reporting refusals or delays in agreeing cost price increases rose from 14% to 15% in 2026. The increase is smaller than the invoice discrepancy figure, but the context matters. The GCA explicitly reiterated its guidance to retailers on handling CPI requests in response to the survey results, citing ongoing global cost pressures.
A cost price increase negotiation depends on evidence. Buyers who question a CPI request will ask what has changed in the supplier's cost base and when. They will look at delivery performance, invoice accuracy, and fill rate alongside the commercial argument.
Suppliers who have clean order and invoice histories, consistent DESADV accuracy records, and strong fill rate data are in a different negotiating position from those raising a CPI request alongside unresolved invoice disputes. The documentation supports the conversation. Unresolved discrepancies undermine it.
How the Retailers Compare
Overall compliance remained strong at 92% across the 14 retailers. Waitrose ranked most compliant for the second consecutive year. Morrisons scored 89%, below the sector average. Amazon remained the lowest-rated retailer at 68%, and the GCA has launched a targeted investigation into Amazon covering supplier payment delays between March 2022 and June 2025.
The GCA moved from the Department for Business and Trade to the Department for Environment, Food and Rural Affairs from 1 July 2026, bringing grocery supply chain oversight closer to food and farming regulation. The structural change signals that supplier protections will sit within a department with greater focus on food supply specifically.
For suppliers, knowing where their retail accounts sit in the compliance rankings matters. A retailer at the bottom of the GCA table is more likely to generate the invoice discrepancy and payment delay issues that the survey captures. That is not a reason to avoid those accounts, but it does change how much attention the trading relationship needs operationally.
Before Golden Quarter
The GCA conference ran at the end of September. Golden Quarter starts in November. The timing is not a coincidence for suppliers who are thinking about this at all.
- Check DESADV accuracy across the last 60 days. Patterns of despatch notification errors that create low-level disputes in September will generate higher-value deductions in November when order volumes double. The window to fix recurring issues is October.
- Reconcile any open invoice disputes before peak orders arrive. An unresolved invoice dispute from August sitting in a retailer's accounts payable queue is not a neutral position. It adds friction to payment processing at the point when the supplier needs fast settlement most.
- Have documented evidence ready for any CPI discussion. If a cost price increase conversation is likely in the next six months, the supporting data should be clean and accessible now. That means consistent fill rate records, accurate invoice histories, and no outstanding discrepancy queues undermining the argument.
- Confirm EDI connections are live and validated for any new UK retail accounts. A new listing confirmed in September needs a tested EDI connection in place before the first Golden Quarter order arrives. DESADV errors on a new account in week one of November leave a mark on a scorecard that is still being built.
Where Electronic Documentation Fits
Retailers' accounts payable systems process at volume. A document that does not pass validation does not go to a human reviewer for consideration. It creates an exception, and exceptions at scale during Golden Quarter become deductions.
For suppliers managing UK retail relationships through SPS Commerce, DESADV exceptions are flagged in real time across all connected accounts, and invoice and order data flows from a single integrated system rather than being managed retailer by retailer. Fewer mismatches between documents means fewer discrepancies landing in a buyer's accounts payable queue during the most expensive eight weeks of the year.