Misleading Advertising by Omission: When a Seller’s Silence Creates Liability

This page is a translation of the original Portuguese text, provided for convenience. It deals with Brazilian law. If there is any discrepancy, the Portuguese version prevails. Read the original in Portuguese

Leaving essential information out of an advertisement is misleading advertising and makes the supplier liable. In vehicle financing with hidden charges and in poorly disclosed automatic-renewal offers, silence about what matters to the consumer has become the center of consumer-law disputes in 2026.

What Makes an Advertisement Misleading by Omission Under the CDC

The Consumer Defense Code (Código de Defesa do Consumidor, or CDC) does not require an ad to contain a false statement before it can be condemned. It is enough that the ad fails to tell consumers what they would need to know to make an informed decision. That is what Article 37, paragraph 3, of Law 8.078/90 provides when it defines as misleading by omission any advertising that fails to disclose essential data about the product or service.

The phrase “essential data” is the heart of the matter. It does not mean just any detail, but one capable of influencing the decision to buy. The final price, payment terms, credit charges, the length of the term, and how to cancel generally belong in that group. When these are missing, buried in tiny print, or sent off to a distant link, the ad leads the consumer to expect something that does not match the reality of the contract.

This type of violation is closely tied to the duty to inform set out in Article 6, item III, and to the clarity requirement of Article 31, both of the Code. The information owed to consumers must be conspicuous, accurate, precise, and easy to notice. The rule rests on a simple premise: consumers become even more vulnerable when the supplier controls the information and chooses what to reveal.

Vehicle Financing and the Hidden Costs of the Offer

The auto industry accounts for a significant share of complaints about advertising omissions. The ad typically highlights a low initial installment or an apparently attractive interest rate, without revealing the components that raise the real amount of the debt. Application fees, contract registration charges, bundled insurance, third-party services, and the so-called Total Effective Cost rarely get the same prominence as the number that catches the eye.

The Total Effective Cost, known by its Portuguese acronym CET, was created precisely to combine all the charges of a credit transaction into a single percentage. National Monetary Council regulations require that it be disclosed clearly and in advance in financing transactions with individuals. When an advertisement states only the nominal interest rate and says nothing about the effective cost, it omits information that the financial system itself recognizes as indispensable.

Article 52 of the Code reinforces this requirement for the provision of credit or financing. It obliges the supplier to inform the consumer, in advance and in an adequate manner, of the price in local currency, the amount of default interest, the annual effective rate, any additional charges provided by law, the number and frequency of installments, and the total amount payable with and without financing. Advertising that contradicts this rule foreshadows a violation that will materialize in the contract.

Examining an actual case often reveals a pattern. The consumer is drawn in by an advertised condition, goes to the dealership, and only then discovers the charges that turn an attractive offer into a far more expensive commitment. The gap between what was promised and what is presented at signing measures the extent of the omission and guides the claims to be made.

It is worth remembering that Article 30 binds the supplier to the content of its advertising. An offer that has been published becomes part of the contract and binds whoever made it. If the ad promised a particular condition, the consumer may demand that it be honored on the exact terms presented, even if the written contract says otherwise.

If the ad promised a particular condition, the consumer may demand that it be honored on the exact terms presented, even if the written contract says otherwise.

Undisclosed Automatic Renewal as a Harmful Practice

The second front in this litigation is growing in the digital environment. App subscriptions, extended warranty plans, benefits clubs, and other recurring services are often sold with the promise of a free or low-cost introductory period. The fact that, once that period ends, the charge automatically renews at the full price usually appears discreetly, outside the main field of view of the offer.

Article 37, paragraph 3, applies here as well. Automatic renewal is essential data because it defines the consumer’s ongoing financial commitment. Leaving it out, or presenting it without prominence proportional to the rest of the offer, misleads the consumer. The consumer believes they are getting a one-time benefit when in fact they are authorizing a continuing relationship of successive payments.

Article 39, item III, rounds out the picture by prohibiting the sending of a product or the provision of a service without prior request. A charge that keeps recurring without a clear, renewed expression of the consumer’s will comes close to that prohibition. Add to this the rule in Article 51, which makes void any clauses that place the consumer at an excessive disadvantage or that are incompatible with good faith.

Objective good faith, the principle that guides every consumer relationship, requires active transparency. It is not enough for the supplier to avoid lying: it must disclose, prominently, whatever changes the consumer’s economic position. Silent renewal defeats the legitimate trust placed in the offer and opens the door to liability.

Legal Remedies Available to Harmed Consumers

Once an omission has been identified, the legal system offers a range of responses that goes beyond simple financial compensation. Article 35 of the Code allows the consumer, when an offer is not honored, to demand specific performance on the terms advertised, to accept another equivalent product or service, or to terminate the contract and recover what was paid, with monetary adjustment, without prejudice to damages.

On the contractual side, the nullity of abusive clauses under Article 51 makes it possible to strike undisclosed charges and recalculate the outstanding balance. The specific relief provided by Article 84 allows court orders to stop an improper charge, suspend automatic renewals, or require the return of money, subject to a daily fine. The refund of twice the amount improperly charged, provided for in Article 42, sole paragraph, applies when the supplier cannot show a justifiable mistake.

Compensation for non-pecuniary (moral) damages is possible when the omission goes beyond mere annoyance and affects the consumer’s dignity or peace of mind, which is common in repeated charges and in credit blacklisting resulting from defective contracts. The analysis depends on the circumstances, the seriousness of the conduct, and its actual impact on the harmed person’s life.

There is also an administrative dimension. Consumer protection agencies may impose sanctions on a supplier that runs misleading advertising, including fines, corrective advertising, and suspension of advertising activity, under Article 56. This route does not depend on an individual lawsuit and reinforces the educational nature of the penalties for omission. Consumers who gather evidence of the offer, the contract, and the charges improve their chances of success on any of these fronts.

Frequently Asked Questions

When does missing information in an ad amount to misleading advertising?

An omission becomes misleading when it concerns essential data, meaning information capable of influencing the decision to buy. Article 37, paragraph 3, of the Consumer Defense Code does not require a false statement: it is enough that the ad fails to disclose a relevant condition, such as the total cost of credit or the existence of automatic renewal, leading the consumer to expect something that does not match the contract.

How can a consumer spot hidden costs in vehicle financing?

The starting point is to compare the advertised offer with the Total Effective Cost presented before signing. This percentage combines interest, fees, insurance, and the other charges of the transaction. When the advertising highlights only the nominal rate and the initial installment, without disclosing the effective cost and the total amount payable required by Article 52, that is a strong sign that essential information was omitted.

What can be done about an automatic renewal charged without clear disclosure?

Under Article 35, the consumer may demand termination of the contract and a refund of the amounts paid, and may also seek the double refund provided for in Article 42 when the charge was improper and there was no justifiable mistake. The specific relief under Article 84 allows a court order to suspend the renewal and stop the charges. Gathering a record of the offer and the history of charges strengthens the claim.

As informações deste artigo são de caráter informativo e não substituem consulta jurídica individualizada. Cada caso possui particularidades que exigem análise específica.