A large percentage on a sale sign answers only half the value question. The other half is the price used as its starting point. With autumn promotions leading into Christmas shopping, checking that denominator is more useful than collecting discount headlines.

This guide compares the regulator’s pricing instructions with an original worked example. The amounts are hypothetical: they do not describe a particular shop or establish that any retailer has broken the rules.

Start with the previous 30 days

The CCPC’s price-reduction guidance explains that a trader announcing a reduction for goods must show the prior price and base the reduction on it. That means the lowest price applied during at least the previous 30 calendar days, excluding the day on which the reduction starts.

A recently increased price is therefore not automatically the correct reference. A recommended retail price or another seller’s price also answers a different comparison question. Extra reference prices should not obscure the required prior price.

Worked example: the denominator changes the claim

Suppose an imaginary coat was sold for €80 during the relevant period, subsequently rose to €100, and is now offered for €72. The change from €100 to €72 is €28, or 28%. But compared with the €80 prior price, the reduction is €8: €8 divided by €80 equals 10%.

Those are calculations from different baselines. Under the regulator’s explanation of an announced reduction, the €80 lowest prior price is the relevant starting point in this scenario. The €72 amount may still be affordable or competitive; that is a separate question from whether a percentage describes the required comparison.

Keep separate promotions separate

The CCPC distinguishes uninterrupted successive reductions within one campaign from separate campaigns occurring within 30 days. One continuing campaign can retain the baseline before its first reduction. A later separate promotion must account for the lowest price in its own preceding period, including an earlier offer.

Do not assume that every promotional technique follows this exact rule. Conditional multibuys, genuinely personalised discounts and services are among the different situations discussed in the guidance. The word “offer” alone does not identify the legal category.

A five-field sale record

Record the exact product and variant; seller and channel; current price; displayed prior price and percentage; and the date of the observation. Save the complete announcement as well as the product price, since a cropped percentage can omit the comparison basis.

If comparing online and in-store prices, label them separately rather than assuming one price history proves the other. Add delivery costs to the household spending decision, but keep them outside a product-only percentage calculation.

The CCPC’s consumer pricing advice explains how pricing information should help shoppers compare. Ask the seller to clarify an unclear reference price and keep its answer. A missing explanation is a reason to investigate, rather than enough evidence to publish an allegation about a business.