Inside self-preferencing complaint under the DMA: the seller's real options

For a third-party seller on Amazon ES, the damage from self-preferencing is rarely dramatic. It arrives quietly – as a visibility drop, a Buy Box loss, or a gradual shift in sponsored-placement costs that is hard to attribute to any single policy decision. The commercial injury is real. The question is whether there is a legal path to address it, and if so, what that path actually looks like in practice.

TL;DRA self-preferencing complaint under the Digital Markets Act (DMA) challenges Amazon's conduct as a designated gatekeeper when it systematically favors its own products or services over those of third-party sellers. On Amazon ES, the realistic options include a formal complaint to the European Commission, a coordinated internal complaint under Amazon's own Digital Services Act (DSA) and Platform-to-Business (P2B) mechanisms, and, where the conditions are met, national enforcement or civil-litigation routes in Spain. Each route carries different timelines, costs, and realistic probabilities of a concrete seller-level outcome.

This analysis covers how the DMA's self-preferencing prohibition actually operates on a Spanish marketplace account, what the procedural paths look like in sequence, and where the genuine decision points are for a seller weighing the cost of action against the cost of doing nothing.

What self-preferencing looks like on Amazon ES – and why it matters to a third-party seller

Self-preferencing, in the DMA's framework, is Amazon giving Amazon-branded or Amazon-owned products a systematic ranking, placement, or visibility advantage over comparable third-party seller products – not on the merits of price, delivery speed, or customer reviews, but because Amazon controls both the platform and the competing product line.

In matters we handle involving Spanish marketplace sellers, the pattern often shows up in one of three ways. First, Amazon Basics or other first-party products appear in the top organic or sponsored positions in categories where the seller competes, even when the third-party seller's product has comparable or better review scores. Second, the Buy Box algorithm routes a disproportionate share of purchase-intent traffic to Amazon's own fulfillment or retail offers. Third, pricing and promotion algorithms appear to penalize sellers whose prices are not aligned with Amazon's preferred price point, effectively compressing their margins in categories where Amazon itself competes.

What makes this a DMA matter rather than a generic complaint is designation. Amazon was formally designated as a gatekeeper under the DMA, meaning it is subject to the Act's obligations – including the self-preferencing prohibition under Article 6 – as a matter of ongoing legal duty, not a voluntary commitment. That designation applies to Amazon's core platform services across the EU, which includes Amazon ES.

The practical significance for a seller: the DMA creates a legal hook that did not exist under earlier competition law. The P2B Regulation and the DSA provide complementary procedural levers. Together, they mean that a seller's complaint is not simply a request that Amazon reconsider – it is a filing against a designated gatekeeper subject to regulatory enforcement.

Is every ranking disadvantage a DMA violation? No. The DMA prohibits systematic preferencing, not every instance of Amazon's first-party product appearing above a third-party offer. Building a credible complaint means identifying the structural pattern, not a single placement event.

How the DMA's self-preferencing prohibition actually works

The DMA's self-preferencing obligation is an access and fairness obligation imposed on gatekeepers, not a per se competition-law infringement requiring proof of market harm in the traditional antitrust sense. That distinction matters for a seller trying to use it.

Under the DMA framework, Amazon must not rank its own products or services more favorably than those of third-party sellers using data or signals generated by the seller's own activity on the platform. This covers organic search, featured placement, and algorithmic recommendations. The obligation applies regardless of whether Amazon can show a business-justification defense of the kind available in traditional competition law – the DMA's structure shifts the burden.

For a seller on Amazon ES, the operative question is whether Amazon's ranking and placement behavior on the Spanish storefront constitutes the kind of systematic, across-category preferencing the DMA is designed to address, or whether it reflects lawful competitive behavior that happens to disadvantage some sellers. That distinction is not always clear at the account level. We regularly see sellers whose data shows a consistent visibility deterioration in categories where Amazon retail is active, but where the proximate cause is genuinely ambiguous from Seller Central data alone.

The DSA and P2B Regulation complement the DMA at the operational level. The DSA requires Amazon, as a very large online platform (VLOP), to provide meaningful statements of reasons for restrictions and to maintain an internal complaint-handling system. The P2B Regulation requires Amazon to set out in clear, accessible terms the main parameters that determine ranking. A seller who has received no adequate explanation for a visibility loss or Buy Box suppression can use the P2B Regulation's ranking-transparency requirement as a basis for a formal challenge before escalating to a DMA complaint.

One more point worth stating plainly: the DMA's enforcement mechanism is primarily Commission-driven. A private seller cannot compel the European Commission to open a proceeding. But a credible, well-documented complaint significantly changes the information available to the Commission and – where national authorities have jurisdiction – to the relevant competition authority in Spain. That is a real lever, even if it is not a direct one.

What is the realistic procedural path for a seller on Amazon ES?

The procedural path for a self-preferencing complaint has three broad stages, and the choice of which stages to pursue – and in what order – is the central strategic decision for any seller.

Stage one: internal complaint under DSA and P2B mechanisms. Before any external filing, a seller should fully exhaust Amazon's internal complaint-handling process, framed under both the DSA's statement-of-reasons requirement and the P2B Regulation's ranking-transparency obligation. This is not merely procedural formality. A well-constructed internal complaint generates a documented Amazon response – or a documented Amazon silence – that is directly useful in any subsequent regulatory filing. In our practice, the internal complaint stage often reveals more about Amazon's actual ranking parameters than the seller previously knew, and occasionally produces a concrete response that addresses part of the commercial problem without further escalation.

Stage two: Commission complaint or national authority referral. If the internal complaint route produces no meaningful response, or if the response confirms a policy that is facially inconsistent with the DMA's self-preferencing prohibition, the next stage is a formal complaint to the European Commission's Directorate-General for Competition, which has lead enforcement jurisdiction under the DMA. National competition authorities – in this case, the Comisión Nacional de los Mercados y la Competencia (CNMC) in Spain – can also receive complaints and, depending on the matter, may refer them to the Commission or act on related national-law grounds.

Stage three: civil litigation in Spain. Where a seller has suffered quantifiable commercial harm traceable to a specific DMA-inconsistent practice, civil litigation in the Spanish courts is a third option. This is the most direct route to a seller-level remedy – a damages award or an injunctive order rather than a regulatory proceeding that benefits all affected sellers collectively. It is also the most resource-intensive path, and the one where evidence quality is most directly determinative.

The decision logic runs roughly as follows: if the notice or policy cites a general ranking parameter change with no seller-specific explanation, the P2B/DSA internal route is the first move, typically over several weeks. If Amazon's response confirms a systematic practice affecting a category, a Commission complaint is the next step, on a timeline that is typically measured in months at best. If the harm is quantifiable and the evidence trail is strong, civil litigation in parallel with or following the regulatory complaint is worth evaluating as a distinct option.

An FBA seller based in Barcelona (spring 2026) came to us after experiencing a sustained visibility drop in a home-electronics sub-category where Amazon Basics had recently expanded. We built the internal-complaint record first – using the P2B ranking-transparency request to generate a written response from Amazon's business team – and used that response, which acknowledged a "relevance algorithm update," to anchor a regulatory complaint filed through the Commission's DMA channel. The matter is ongoing, but the internal-complaint stage produced a partial reinstatement of the seller's featured placement in one sub-category within the first 90-day window.

How does the DMA interact with EU marketplace suspension on Amazon ES?

Not every seller who contacts us about self-preferencing is asking about a ranking problem. A significant share come to us after an account suspension or listing deactivation that they believe is connected to Amazon's preference for its own competing product. That connection – between competitive displacement and platform enforcement action – is an important but contested legal question.

The DSA and P2B Regulation are directly relevant here. A suspension or delisting that follows shortly after a seller's product achieves high visibility in a category where Amazon retail competes is not, on its own, evidence of a DMA violation. Amazon has legitimate enforcement tools, and the mere sequence of events does not establish causation. But it is a pattern we document carefully, because it is material to any regulatory or civil argument about pretextual enforcement.

Under the DSA, Amazon must provide a statement of reasons for any suspension or restriction, and it must maintain an accessible internal complaint-handling mechanism. If the statement of reasons does not adequately explain the basis for the action – or if the stated reason is demonstrably inconsistent with the pattern of enforcement across similarly-situated sellers – that record supports both an internal DSA complaint and, in the appropriate case, a Commission filing.

The complete guide to EU marketplace regulation for sellers covers the full landscape of DSA, DMA, and P2B obligations in detail, including how they interact with account-level enforcement actions. For sellers on German storefronts, the procedural considerations are somewhat different; responding to a German marketplace suspension involves additional Bundeskartellamt dimensions that do not apply in the same form in Spain. And for sellers with cross-border EU operations, the French marketplace suspension context illustrates how national enforcement differs even within the same EU regulatory framework.

The core point for a seller facing a Spanish suspension in a competitive category: the suspension mechanism and the self-preferencing mechanism are legally distinct, but they draw from the same procedural toolkit. A well-built DSA internal complaint about the suspension strengthens any parallel DMA complaint about the underlying competitive conduct.

The seller's real decision points: what are the trade-offs?

The myth among EU sellers is that once a platform suspends them, or once a ranking shift cuts their revenue, there is nothing to do but accept it. That is wrong. But the realistic counter is not that every seller should file a Commission complaint. The realistic counter is that the DMA and its companion rules create a range of graduated options, and the right choice depends on the specific facts, the seller's appetite for a sustained engagement, and the commercial case for action.

Here are the genuine trade-offs.

The internal complaint route is relatively low-cost and often underused. It produces documented evidence. It sometimes produces a concrete partial remedy. Its limitation is that it depends on Amazon's good-faith engagement, which varies by category and by the specificity of the complaint. A well-drafted internal complaint – grounded in specific P2B ranking-parameter disclosures and specific DSA statement-of-reasons requests – performs materially better than a generic objection.

A Commission complaint does not produce a seller-specific remedy. It contributes to a regulatory record. It may, in time, produce a Commission decision that changes Amazon's conduct across the EU. For a seller with a significant and ongoing commercial injury, and for whom the alternative is continued revenue loss, the contribution-to-record argument has real weight. For a seller with a one-time dispute, it is probably not the primary vehicle.

Civil litigation in Spain is the route most likely to produce a seller-specific financial remedy, and the most demanding in terms of evidence and resources. It requires demonstrating the causal connection between Amazon's self-preferencing conduct and the seller's quantifiable loss – a meaningful evidentiary threshold. In matters we handle, this route is typically evaluated after the internal complaint record is built and the Commission complaint is filed, not instead of them.

Parallel tracks – internal complaint plus Commission filing plus civil action – are not mutually exclusive. They serve different purposes and run on different timelines. The discipline is in coordinating the evidence trail so that each stage strengthens the next.

A clothing seller on Amazon ES (winter 2025) presented a clear pattern: a sustained impressions drop in a fashion sub-category where Amazon Fashion had recently launched a competing line, accompanied by an account-health notice about product authenticity documentation that the seller believed was pretextual. We separated the two matters procedurally – handling the account-health notice through the standard compliance route while building a parallel P2B/DSA complaint about the ranking change. The separation preserved the seller's trading relationship with Amazon while keeping the competitive-conduct complaint open on its own merits.

What evidence does a credible self-preferencing complaint actually require?

A credible complaint – whether to Amazon's internal system, to the Commission, or to a Spanish civil court – requires more than a seller's intuition that Amazon is playing favorites. The evidentiary minimum is a documented pattern, not a single data point.

The core evidence set for a DMA self-preferencing complaint typically includes the following elements. Systematic ranking data showing the seller's position relative to Amazon-branded or Amazon-retail products in the same category over a meaningful period – ideally extracted from third-party tools and cross-referenced with Seller Central data. A record of the seller's product attributes (price, delivery performance, review score, fulfillment method) relative to the competing Amazon product, to establish that any ranking disadvantage is not explained by performance differentials. Any statements or communications from Amazon that describe the ranking or placement parameters in ways inconsistent with the DMA's non-discrimination requirement. The internal P2B ranking-transparency request and Amazon's response – or Amazon's failure to respond adequately.

We regularly see sellers who have strong commercial intuitions about self-preferencing but have not preserved the contemporaneous evidence. Seller Central data is not retained indefinitely, and third-party ranking tools generate snapshots rather than continuous records. The practical implication: if a seller suspects a self-preferencing pattern, the time to begin evidence preservation is immediately, not after the decision has been made to file a complaint.

One short definitional clarification for record-keeping purposes: a self-preferencing complaint is a formal representation to a regulatory authority or to the platform itself that the gatekeeper has violated its DMA Article 6 obligation to treat data from third-party sellers on equal terms with data from its own competing services, in the allocation of platform visibility and placement. That definition matters because it sets the evidentiary scope – not all ranking changes, not all Buy Box decisions, but specifically those driven by Amazon's use of third-party seller data to advantage its own competing products.

What does the Commission enforcement process actually look like for sellers watching from the outside?

Understanding the Commission's DMA enforcement process helps sellers calibrate what a complaint contributes and what it does not deliver directly.

The Commission has exclusive enforcement jurisdiction over gatekeeper compliance under the DMA. When it opens a formal non-compliance investigation, it does so on its own initiative or following a complaint. The investigation process involves formal information requests to the gatekeeper, access to data, and, where a violation is found, the power to impose substantial fines and to require behavioral remedies. DMA fines can reach a significant percentage of the gatekeeper's global annual turnover, which in Amazon's case represents a material deterrent.

For a third-party seller filing a complaint, the process is this: the complaint is reviewed by Commission staff, who may or may not incorporate its substance into an active investigation. The seller receives no binding timeline commitment for a response. The Commission has broad discretion over which complaints to prioritize.

What a complaint does contribute is a documented data point in the Commission's intelligence picture. When multiple sellers in the same category, across multiple EU storefronts, submit consistent complaints about the same category-level ranking pattern, that contributes to the threshold of evidence the Commission needs to initiate a formal proceeding. In that sense, a well-constructed individual complaint is not just an individual act – it is part of a collective evidentiary record.

For a seller whose primary concern is their own account, the Commission route is a medium-to-long-term play. The DSA internal complaint route is the immediate operational lever. Civil litigation is the route to a seller-specific remedy. The Commission complaint is the contribution to a structural outcome that, if it produces a Commission decision, changes the rules for all sellers.

If a first filing to Amazon's internal complaint system came back with a generic response or no meaningful engagement, a second submission – reframed around the specific DSA statement-of-reasons requirements and the P2B ranking-parameter obligations – can generate a materially different response. The framing and specificity of the complaint matter considerably. To have that second submission reviewed before deciding on the Commission route, email info@tutamenlaw.com.

Related areas

• EU Marketplace Regulation – DMA, DSA, P2B and national enforcement for EU-based sellers
• Amazon Account Reinstatement – Plan of Action, appeal and reactivation across all surfaces
• IP and Brand Registry – rights-owner complaints, counter-notices and retraction on Amazon

Frequently asked questions

How long does resolving self-preferencing complaint under the DMA usually take on Amazon ES?

Resolution timelines vary considerably depending on the route chosen and the complexity of the evidence. The internal complaint stage – using DSA and P2B mechanisms – typically produces a formal response within several weeks, though substantive engagement from Amazon can take longer. A Commission complaint operates on a regulatory timeline that is typically measured in months at minimum for an initial acknowledgment and considerably longer for a formal investigation. Civil litigation in Spain is a multi-year process in contested matters. In our experience, sellers who begin with a well-built internal complaint and use that record to escalate see the fastest concrete movement at the account level, even if the broader regulatory process moves more slowly.

What are the main risks if I handle self-preferencing complaint under the DMA alone?

The primary risk of proceeding without specialist support is filing a complaint that is too generic to generate a meaningful response. Amazon's DSA and P2B complaint mechanisms require specific, technically grounded submissions – a vague objection to ranking changes is unlikely to trigger the statement-of-reasons obligations that produce useful evidence. A second risk is failing to preserve contemporaneous evidence before filing, which reduces the strength of any subsequent Commission or civil complaint. A third, more serious risk: raising the self-preferencing issue in a way that prompts Amazon to initiate an account-compliance review without a pre-built response strategy, effectively combining two distinct problems into one.

Do I need a lawyer for self-preferencing complaint under the DMA?

A lawyer is not a legal requirement for filing a Commission complaint or an internal DSA complaint. But the quality of the complaint determines what it produces. In matters we handle, the difference between a generic complaint and a technically grounded one – citing specific DMA obligations, specific P2B ranking-parameter disclosures, and specific DSA statement-of-reasons failures – is the difference between a pro forma response and a substantive engagement. For sellers considering civil litigation in Spain, attorney representation is a practical necessity given the evidentiary and procedural requirements. For the internal and Commission complaint stages, the value of specialist input is in complaint construction and evidence sequencing rather than formal representation.

About Tutamen

Tutamen is an independent law firm for online marketplace sellers. We represent Amazon, Walmart, Etsy and eBay sellers in account deactivations, frozen-funds recovery, intellectual-property disputes, arbitration and Notices of Dispute, and US federal Schedule A defense, plus EU marketplace regulation. Our work is attorney-led and confidential, with fees quoted up front. We act for founders, brand owners and in-house teams who need a specialist for a marketplace dispute. Our EU regulation practice is attorney-led and operates under strict client confidentiality; fixed fees are quoted after a short review of the account and the regulatory context. To discuss your situation, email info@tutamenlaw.com.

Disclaimer: This article is general information, not legal advice, and does not create an attorney-client relationship. Marketplace policies and the law change, and every account and case is different. For advice on your situation, contact Tutamen at info@tutamenlaw.com.