Does the Omnibus 30-day rule apply to flash sales?

Short answer: yes. A flash sale — a short, time-limited discount — is still an announcement of a price reduction, so the Omnibus 30-day lowest-prior-price rule applies just as it does to any other sale. The brevity of the offer does not exempt it.

Under Article 6a of the Price Indication Directive, as amended by the Omnibus Directive (2019/2161, applying from 28 May 2022), whenever you announce a price reduction you must indicate the prior price, defined as the lowest price you applied during at least the 30 days before the reduction. Nothing in the rule turns on how long the reduced price lasts. A two-hour flash sale, a 24-hour deal, and a two-week promotion are treated the same way for the purpose of the reference price.

What this means in practice

The struck-through “was” price in your flash sale must be the genuine lowest price you charged in the preceding 30 days — not an inflated figure introduced just before the event, and not the recommended retail price dressed up as your own prior price. If you show “−40% for 3 hours only”, that 40% must be calculated against the real 30-day low.

• Do not raise the price shortly before the flash sale to make the discount look bigger — the reference is the lowest price in the last 30 days, so the bump is ignored (or worse, exposes the display as misleading).
• Keep a price history. If challenged, you must be able to evidence that the reference price was genuinely the lowest applied over the 30-day window.
• Percentage and “save €X” wording count too, not just was/now displays — the same 30-day basis applies to how the reduction is expressed.
• Back-to-back flash sales are a red flag. If a product is almost always “on flash sale”, the reference price you keep striking through may not reflect a genuine higher prior price, which regulators can treat as misleading.

A quick worked example

A gadget sold at €50 for the last 30 days. You run a 4-hour flash sale at €35 and advertise “was €50, now €35”. This is fine: €50 was genuinely the lowest price in the prior 30 days. But if the gadget had actually been €40 for most of that month and you quietly lifted it to €50 the day before, the prior price is €40 — and advertising “was €50” during the flash sale would be non-compliant.

For the full mechanics, see our Omnibus overview and complete Omnibus guide. The rule is about honesty of the reference price, and a flash sale is no exception.

This answer is provided for educational purposes only and does not constitute legal advice. National implementations and derogations vary and change over time; consult a qualified lawyer in the relevant jurisdiction before making compliance decisions for your business.