According to DECO PROteste (27 November 2025), since May 2022 a sale with a price reduction is only lawful if the discount is measured against the lowest price charged in the same shop in the previous 30 consecutive days; labels and lists must show the new price and the lowest previous price. In 2025, DECO found shops not complying and comparisons with manufacturer recommended prices (PVPR) that could mislead. Black Friday 2026 is on 27 November. For paid ads, the practical conclusion is: the “was/now” must be true and documented. This article is not legal advice.
What the law requires, according to sources
DECO PROteste indicates that, since May 2022, a sale with a price reduction is only lawful if the discount is measured against the lowest price at which the product was sold in the same shop in the 30 consecutive days before the reduction. Labels and lists must show the new price and the lowest previous price, and showing the percentage discount is optional. 4gnews, a secondary source citing ASAE, adds that this period includes other sales or promotions.
4gnews’ example: “before €699, now €499” only makes sense if €699 was a usual price and not a price the product had already been selling near €499.
What DECO PROteste found in 2025
The main investigation ran from 1 to 14 November 2025, with additional visits on 3 and 4 and on 24 and 25 November. DECO found shops that did not apply the discount against the lowest price of the previous 30 days, struck-through prices that did not meet the requirement and products on sale at prices higher than days earlier. It describes concrete examples, including a 25% discount calculated on a struck-through price the shop had never charged.
DECO PROteste asked ASAE to strengthen enforcement on Black Friday. We found no DECO guidance specific to 2026 nor enforcement changes for this year.
Reference price on Black Friday
- Keep daily price history
- See the lowest price of the previous 30 days
- Use that price as “before” in ads and feed
- Save screenshots on launch day
- Seek legal advice for doubtful cases
The PVPR problem
DECO PROteste warns that comparing the promotional price with the manufacturer’s recommended retail price (PVPR) can mislead the consumer into thinking they get a real discount. According to the study, almost all chains analysed used this tactic, with one exception, and expressions such as “Super Poupança”, “Melhor preço” and “Promoção oportunidade” appeared next to PVPR-based percentage discounts.
If your ads or pages show “from X to Y” with X coming from the manufacturer, seek legal advice and prefer to show your own lowest price of the 30 days.
Why this is a PPC matter
The ad text, price extension, Merchant Center feed and landing page state a price and sometimes a discount. If one of these shows an inflated “before” price, or if feed and page are misaligned, the ad may be misleading, and responsibility lies with the advertiser. Since automation generates text variations and chooses assets, it’s worth knowing whether AI adds discount percentages on its own.
On Black Friday, ad volume is higher and so is the cost of a price error.
The “was/now” must be true and documented. In advertising, a price is a claim.
Price records: the evidence that protects the shop
Keep, per product, the daily price history for the last 60 days, with date. Before launching a promotion, check what the lowest price of the previous 30 days was and use it as reference. Also keep screenshots of ads and pages on launch day.
In case of complaint or inspection, this record is your defence. Many shops don’t have it, and only discover the lack when they need it.
Pre-promotions and “Black November”
4gnews says discounts can start weeks earlier, with “Black November” and “Black Week”. If you lower the price in early November, the lowest price of the 30 days for Black Friday becomes that lower price, and Black Friday’s “real” discount gets smaller.
This is a practical consequence of the rule: advancing discounts reduces the possibility of advertising big percentages later. Plan the price and ad calendar together.
Checklist for your ads
Ad, extension, feed and page prices match; “was/now” based on the lowest price of the 30 days, not unfounded PVPR; no automatically generated percentages you haven’t confirmed; clear start and end dates; real stock; visible conditions (shipping, deadlines); and screenshots saved. Ask the agency to confirm the point on AI and automatic texts.
If you sell in several countries, rules may differ. Confirm those applicable in each market.
Questions for your manager
How do we define the “before” price in ads? Do we keep price history? Does AI add discounts without approval? Who validates feed prices before each campaign day? And do we have legal advice for our promotions?
If you want to prepare a price and promotions checklist for Black Friday, with your feed, ads and pages, I can help, and the final text should be validated by a lawyer.
Frequently asked questions
What is the 30-day rule?
According to DECO PROteste, the discount must be measured against the lowest price charged in the same shop in the previous 30 consecutive days, since May 2022.
Can I use PVPR as a reference price?
DECO warns it can mislead. Seek legal advice.
When is Black Friday 2026?
27 November 2026, according to 4gnews.
Sources consulted
Keep reading
- Black Friday 2026: fake sites, phishing and how to protect your brand and customers in ads
- Seasonality adjustments in Google Ads for Black Friday 2026: what they do, for which campaigns and when to use
- Campaign calendar for Portugal from November 2026 to March 2027: the platform and business dates that matter