Before you act on self-preferencing complaint under the DMA: a checklist

TL;DRA self-preferencing complaint under the Digital Markets Act (DMA) is a formal challenge to conduct by a designated gatekeeper – in this context, Amazon – that ranks or displays the platform's own products, services, or offers more favorably than those of third-party sellers, in ways the DMA prohibits. On Amazon ES, this matters immediately: if your listings are being systematically pushed down in search results, your buy-box access is being distorted, or your advertising reach is being structurally limited compared to Amazon's own retail arm, you may have a cognizable DMA claim. EU sellers are not without leverage once a platform acts against them – but acting on that leverage requires methodical preparation before you file anything.

This checklist walks through the preparation a seller on Amazon ES should complete before sending any complaint to the European Commission, invoking internal complaint procedures under the Platform-to-Business (P2B) Regulation, or pressing a claim through any other EU channel. Each phase is discrete. You can complete several steps independently; others require legal judgment about evidence weight and procedural timing.

As enforcement automation has tightened across EU marketplaces, the window between a commercially damaging event and the expiry of the most useful procedural options can be surprisingly short. Getting the sequence right matters as much as having the facts.

Phase 1: What exactly is self-preferencing under the DMA, and does your situation qualify?

The DMA's self-preferencing prohibition is specific: it targets a gatekeeper that ranks its own goods or services more favorably than those of third-party business users in its core platform services, unless that difference is objectively justified. Before you spend time or money on a complaint, the threshold question is whether what happened to your Amazon ES account fits that definition – or whether it is something else entirely.

Self-preferencing under the DMA is distinct from a standard account suspension, a policy enforcement action, or an intellectual-property takedown. It is also distinct from a listing suppression triggered by a fulfilment metric. The DMA concern is structural, recurring favoritism toward Amazon's own competing offer in ranking, search display, buy-box allocation, advertising inventory, or data access – not a one-time algorithmic glitch or a performance-based restriction that applies equally to all sellers.

In matters we handle for Amazon ES sellers, the most common qualifying patterns are: consistent suppression of third-party listings in organic search results when Amazon Retail holds equivalent inventory; buy-box logic that defaults to Amazon's own offer even where a third-party seller's price, dispatch time, and ratings are competitive; and advertising placement rules that give Amazon's own products preferential access to high-visibility slots.

What does not qualify – regardless of how frustrating it feels commercially – is a performance-based ranking difference tied to your seller metrics, a one-time pricing anomaly, or a fee structure that applies uniformly to all sellers. The DMA's Article 6(5) prohibition targets differential treatment of the gatekeeper's own output. Uniform rules, even commercially disadvantageous ones, sit outside that scope.

Checklist – Phase 1:

1. Identify the specific commercial harm: which listings, which search terms, which categories, and over what period.
2. Confirm Amazon ES is the relevant surface and that the conduct involves ranking, display, or access – not a policy enforcement or IP action.
3. Establish that Amazon operates a competing retail or private-label offer in the same product category on ES.
4. Distinguish the pattern from normal metric-based ranking variation: do the same listings perform normally when Amazon Retail is out of stock in that category?
5. Confirm the gatekeeper designation: Amazon was formally designated as a gatekeeper under the DMA, meaning the Act's Article 6 obligations apply to its core platform services including Amazon Marketplace ES.

If steps 1 through 5 all yield affirmative answers, you have a plausible factual basis to continue. If any step reveals a different explanation for the harm – a metrics issue, an IP dispute, a fulfilment problem – the right instrument is different, and the DMA complaint route would be premature. Our practice works through exactly this diagnostic step first, because misrouting a complaint wastes the seller's time and can foreclose better options.

Phase 2: Have you gathered the evidence you will need?

A DMA self-preferencing complaint without documentary evidence is not a complaint – it is an allegation. The European Commission and, where relevant, national competent authorities expect business users to provide concrete commercial data that supports the claim of differential treatment. Gathering that data is the seller's job before filing.

The P2B Regulation, which runs alongside the DMA and applies to Amazon ES directly, independently requires Amazon to explain in its terms the main parameters it uses for ranking. That transparency obligation is the starting point for evidence: request and preserve Amazon's published ranking parameter statements for the ES marketplace, and document where actual outcomes diverge from what those statements would predict.

In matters we handle, the evidence package that tends to support a well-formed complaint includes the following:

• Systematic search-result captures – screenshots or API-level records – showing the seller's listings versus Amazon Retail or Amazon private-label listings across the same search terms over a meaningful period (several months is more persuasive than a snapshot).
• Buy-box win-rate data from Seller Central, stratified by category and time period, compared against your pricing, dispatch time, and seller ratings at the same moment.
• Advertising placement logs showing relative impression share and cost-per-click for your category versus Amazon's own listings when both bid on comparable terms.
• Correspondence with Amazon – Seller Central messages, Account Health notifications, policy notices – that touches on the relevant listings or categories during the relevant period.
• Any prior P2B complaints or internal Amazon escalations and their responses, because the Commission will want to know whether internal remedies were attempted.

Checklist – Phase 2:

1. Download and preserve all relevant Seller Central data for the affected period. Data can be overwritten or become inaccessible over time – preserve it now.
2. Capture and timestamp search-result pages for the key search terms on Amazon ES, both as a logged-in seller and, where possible, as a neutral browser session.
3. Obtain and archive Amazon ES's published ranking and buy-box parameter statements (available in the BSA and in Amazon ES seller help documentation).
4. Extract buy-box win-rate history and correlate it against your price and fulfilment data at the same timestamps.
5. Compile all Amazon Seller Central correspondence and Account Health records for the affected categories and period.
6. Record any prior attempt to raise the issue through Amazon's internal complaint mechanism under the P2B Regulation and preserve the response (or the absence of one).

The quality of evidence collected at this stage is the single biggest variable in whether a complaint leads anywhere. Retroactively reconstructing what search results showed six months ago is difficult; contemporaneous captures are far more persuasive. Our complete guide to EU marketplace regulation for sellers sets out the broader evidentiary standards across DMA, DSA, and P2B matters, and is worth reading alongside this checklist if you are new to these instruments.

Phase 3: Which procedural route is right for your situation?

The EU regulatory architecture gives a seller on Amazon ES more than one procedural route – and choosing the wrong one early can limit later options or delay relief. This is the phase where legal judgment matters most, because the routes have different scopes, different timelines, and different realistic outcomes.

The three main routes for a DMA self-preferencing complaint are: a complaint to the European Commission directly under the DMA; a complaint to or notification through a national competent authority designated to assist the Commission; and a private law claim before a national court, where the DMA's provisions may be used to support a claim under applicable national competition law or unfair-practices rules. These routes are not mutually exclusive, but they have different evidentiary and resource demands, and sequencing them matters.

A Commission complaint under the DMA is the most direct route, but it is also the longest path to any outcome that changes your situation. The Commission investigates gatekeepers at a systemic level; it does not adjudicate individual seller disputes. What a Commission complaint can achieve is triggering an investigation into Amazon's conduct generally – which may eventually change the practice that is harming you, but will not release your funds or reinstate your listings in the near term.

The P2B Regulation's internal complaint mechanism is faster and more specific to your account. Amazon is required to operate an internal complaint-handling system accessible to business users on Amazon ES, and it must handle complaints within a reasonable time. A well-documented P2B complaint about differential ranking treatment is a concrete, documented step that also creates a paper trail useful for any subsequent Commission or court proceeding. It is almost always the right first move.

For suspension situations – where Amazon ES has deactivated a listing or an account alongside or because of a self-preferencing-adjacent enforcement action – the Digital Services Act (DSA) statement-of-reasons mechanism is also relevant. Amazon as a Very Large Online Platform (VLOP) under the DSA must provide a statement of reasons for any restriction it imposes on a business user, and must operate an internal complaint system. If a suspension accompanies the self-preferencing conduct, pursuing the DSA statement of reasons in parallel preserves that route. For related suspension situations, the analysis of German marketplace suspension options illustrates how these instruments interact in practice.

Checklist – Phase 3:

1. Confirm whether you have already attempted Amazon's internal P2B complaint mechanism and, if so, what response you received and when.
2. Determine whether a listing suspension or account restriction accompanies the self-preferencing conduct – if so, identify whether a DSA statement of reasons has been issued and whether the DSA internal complaint deadline has been triggered.
3. Assess the urgency of commercial relief: if the harm is ongoing and severe, the sequence matters – internal P2B first, then escalation to the Commission, with the national-court route assessed separately.
4. Identify the correct national competent authority for Spain (as the marketplace in question is Amazon ES), which may be a designated authority under Article 40 of the DMA for coordination with the Commission.
5. Consider whether the self-preferencing conduct also engages Spanish or EU competition law (Article 102 TFEU dominance abuse), which can be run through national competition authorities in parallel.
6. Do not assume the Commission complaint and the P2B complaint are interchangeable – they have different scope, different addressees, and different timelines.

A micro-case is instructive here. A cookware brand selling on Amazon ES came to us after observing that its listings in a mid-price category were consistently ranked below Amazon's own private-label equivalent, even when the brand's price, ratings, and Prime eligibility were comparable or better (summer 2026). We mapped the evidence over four months, filed a structured P2B complaint through Amazon's internal mechanism citing the ranking parameter discrepancy, and simultaneously documented the pattern for potential escalation to the Commission. The internal complaint produced a written response within several weeks; the response did not resolve the conduct but created the documented foundation for the next step.

Phase 4: What are your decision points and trade-offs before filing?

Every seller reaching this phase faces a real commercial question: is filing a formal complaint the right move for your business right now, or are there better near-term options? A suspension under EU rules can look final – but the realistic picture is more nuanced, and the decision to escalate formally has trade-offs worth understanding before you act.

The case for filing early is straightforward. DMA enforcement is new, and the Commission is actively building its enforcement record on gatekeeper conduct. A well-documented complaint from a business user on Amazon ES contributes to that record and, in systemic cases, can influence how the Commission frames its investigation. If your commercial damage is material and ongoing, waiting compounds the loss. The P2B internal complaint in particular costs little and creates rights.

The case for pausing involves a different calculation. A formal DMA complaint to the Commission is a long-duration process. It does not produce immediate commercial relief. If your primary need is to restore listings or unblock revenue in weeks rather than months or years, the DMA complaint route alone will not deliver that. In those situations, the DSA statement-of-reasons process and internal escalation are more time-relevant. For sellers with a concurrent account suspension, the reinstatement path through Amazon's own mechanisms – pursued with legal precision – is often the faster route to restoring revenue, while the DMA complaint runs in parallel as a longer-term instrument.

There is also a relationship dimension. Some sellers on Amazon ES are in commercial negotiations or have Amazon Vendor relationships that they want to preserve. A formal Commission complaint is a public step; a P2B internal complaint is not. The sequencing can be structured to protect the relationship dimension while still creating a documented record.

The myth that EU sellers have no leverage once a platform restricts them is exactly that – a myth. The DMA, DSA, and P2B Regulation give EU-based and EU-selling business users a range of procedural rights that did not exist before 2023. What matters is using them in the right order, with the right evidence, at the right time. Our practice builds the statement-of-reasons and internal-complaint case, and uses the DSA/P2B/DMA levers that apply to your situation.

Checklist – Phase 4:

1. Quantify the ongoing commercial harm as specifically as you can – lost sales volume by category, lost buy-box win rate, lost advertising visibility – to determine urgency.
2. Identify whether any Amazon relationship (Vendor Central, Brand Registry, Transparency enrollment) could be affected by a formal escalation, and assess whether that changes the sequencing.
3. Confirm whether a DSA internal complaint deadline is running: under the DSA, Amazon must provide a statement of reasons for restrictions and operate an internal complaint mechanism – time limits on invoking that mechanism may apply.
4. Decide whether to pursue the P2B internal complaint first (almost always recommended), or whether circumstances warrant going directly to the Commission or national authority.
5. Assess whether the national competition law route (Article 102 TFEU / Spanish competition law) provides a faster path to interim relief than the DMA Commission process.
6. Get a written legal assessment of the evidence package before filing – a complaint that is filed before the evidence is assembled can be rejected or ignored, and a weak first filing affects how later steps are received.

If a first attempt at Amazon's internal system already came back with a non-substantive response, a second, more precisely framed filing – or immediate escalation to the Commission – may be what is still open. Email info@tutamenlaw.com to have a second read of what you already filed and what the realistic next step is.

Phase 5: Practical pre-filing checks across all routes

Regardless of which procedural route you choose, a set of practical checks applies universally. Skipping them is the most common reason a well-founded complaint fails to gain traction at the intake stage.

Is your entity correctly identified? The business user making a complaint under P2B or DMA must be identifiable as the contracting party on Amazon ES. If your EU sales run through a non-EU entity, or if there is a holding structure between you and the Amazon ES seller account, this affects standing and should be addressed before filing.

Have you preserved evidence in a format that can be submitted? Raw screenshots are a start, but they need timestamps, metadata, and a chain of custody that confirms when they were taken and by whom. For a Commission complaint, the more structured the evidence presentation, the better.

Do you understand what relief you are asking for? The Commission does not grant individual remedies to individual sellers. A Commission complaint seeks systemic change. If you want individual relief – your listing restored, your buy-box access corrected, your specific account situation remedied – the P2B, DSA, and national-court routes are more directly responsive.

For sellers dealing with a concurrent suspension or restriction in another EU market, the same analytical approach applies with market-specific adjustments. What sellers should know about UK marketplace suspension after Brexit explains how the post-Brexit regulatory divergence affects sellers operating across both EU and UK surfaces, including when EU DMA rights no longer apply to UK operations and when separate mechanisms are needed.

Checklist – Phase 5:

1. Confirm the legal entity registered on Amazon ES and verify it matches the entity making the complaint.
2. Organize evidence in a structured form: a chronological narrative, supporting data exports, and timestamped captures.
3. Identify specifically what commercial outcome you need from each route (systemic change vs. individual relief vs. compensation), and match the route to the outcome.
4. Check whether Amazon's internal complaint response, if any, cited a specific BSA provision or policy reason – this is the starting point for any counter-argument.
5. Determine whether the conduct affects other sellers in the same category on Amazon ES – evidence of a pattern affecting multiple business users strengthens a Commission complaint considerably.
6. Confirm your timeline: note the date the harm became apparent, the date of any Amazon notice or response, and the date of any prior filing, so that deadlines under the DSA internal complaint mechanism are not inadvertently missed.

A second micro-case here. An electronics accessories brand on Amazon ES (winter 2026) came to us after its flagship product's ranking dropped sharply in organic search following the launch of an Amazon Basics equivalent in the same subcategory. The seller had already submitted an informal message through Seller Central asking why rankings had changed; it received a generic response. We reconstructed the timeline, organized the search-capture evidence, and filed a structured P2B complaint citing the specific ranking-parameter discrepancy and the temporal correlation with the Amazon Basics launch. The complaint produced a substantive written response – not a resolution, but a documented foundation for escalation that changed the seller's negotiating position on a related Brand Registry matter.

Phase 6: Checking your own position before committing to a complaint

The checklist so far has focused on building the complaint. This phase runs in the other direction: checking whether anything in your own account position weakens the complaint or creates a vulnerability you should address first.

A self-preferencing complaint gains credibility when the complaining seller is in demonstrably good standing on the metrics that Amazon controls. If your Account Health Rating shows open policy violations, if your fulfilment metrics are below Amazon ES standards, or if there are unresolved A-to-z Guarantee claims or chargeback disputes on the account, Amazon will argue that any ranking or buy-box disadvantage is performance-based, not structural. That argument is not necessarily right – but you need to be able to refute it with data.

What does a well-positioned complainant look like? A seller whose Account Health is clean, whose fulfilment metrics meet or exceed benchmarks, whose pricing is competitive, whose listings are fully policy-compliant, and whose performance data shows a decline that correlates with Amazon's own competing offer appearing in the category – not with any change in the seller's own behavior. Anything that deviates from that profile should be addressed and documented before the complaint is filed.

Does this mean a seller with imperfect metrics cannot pursue a DMA complaint? No. But it does mean you need a clear answer to the counterargument that performance explains the difference, not favoritism. That answer needs to be in the evidence package.

Checklist – Phase 6:

1. Review your Amazon ES Account Health Rating and resolve any open violations or warnings before filing.
2. Check fulfilment and defect-rate metrics for the relevant period and confirm they meet Amazon ES benchmarks.
3. Verify that the affected listings are fully compliant with Amazon ES listing policies and content requirements.
4. Confirm your pricing at the relevant time was competitive or better than Amazon's own offer in the same category – and document it.
5. Assess whether any A-to-z claims, chargebacks, or IP complaints on the account could be cited by Amazon as an alternative explanation for any ranking disadvantage.
6. Run the counter-analysis: if Amazon says the ranking difference is performance-based, what is your specific factual rebuttal?

This phase is not about defeating the complaint before it starts. It is about making the complaint as strong as possible by removing the easiest counterarguments. In matters we handle, a clean account position combined with a well-evidenced pattern of differential treatment is a significantly more persuasive foundation than even strong data presented from a seller account with open issues.

Related areas

• EU Marketplace Regulation – Complete Guide for Sellers – the full DMA, DSA, and P2B framework explained for operators
• German Marketplace Suspension – how EU regulatory instruments interact with account deactivation in practice

Frequently asked questions

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

The timeline depends sharply on which route you use. Amazon's internal P2B complaint mechanism typically produces a response within several weeks – though the response may not resolve the underlying conduct. A complaint to the European Commission is a long-duration process measured in months to years, because the Commission investigates systemic gatekeeper conduct rather than individual seller disputes. National competition authority proceedings sit somewhere between those extremes. This is why most sellers pursuing a DMA complaint on Amazon ES are advised to use the P2B internal mechanism first and treat the Commission route as a parallel, longer-term instrument – not a substitute for immediate relief.

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

The most common risks are filing the wrong instrument for the outcome you actually need, submitting an evidence package that is too weak to support the claim, and triggering an escalation that damages an Amazon commercial relationship without achieving the intended result. There is also a sequencing risk: filing a Commission complaint before exhausting internal P2B remedies may weaken the Commission filing, since regulators typically expect business users to have attempted the platform's own complaint mechanism first. Additionally, DSA statement-of-reasons and internal-complaint deadlines can run without the seller realizing they have been triggered, foreclosing that route.

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

You are not legally required to retain a lawyer to file a P2B internal complaint or a Commission complaint under the DMA. But the evidence standards, sequencing decisions, and trade-off analysis described in this checklist require legal judgment – and a misrouted or under-evidenced complaint rarely gets a second chance in the same form. For sellers whose commercial harm is material and ongoing, attorney-led handling ensures that each step builds toward the best available outcome without foreclosing later options. Tutamen's work on EU marketplace regulation is attorney-led, confidential, and priced on a fixed-fee model quoted up front after a short review of your situation.

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 marketplace regulation practice covers DMA self-preferencing complaints, DSA statement-of-reasons proceedings, P2B internal complaint filings, and related account suspension and delisting matters across EU surfaces. Services are available in English. To discuss your situation, email info@tutamenlaw.com.

Page authored by Dmitri Aronov, Partner, EU Marketplace Regulation, Tutamen.

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.

Written by Dmitri Aronov, Partner, EU Marketplace Regulation. Published September 11, 2026.