Marketplace Payment Compliance: PCI, KYC, AML, and Escrow

A marketplace can have a perfectly functional checkout and still have the wrong payment architecture.

The problem usually becomes visible when money stops following the simplest possible route. A buyer pays $500, but the marketplace does not necessarily receive $500 as ordinary revenue. Part may belong to a seller. The platform may collect a commission. Funds might need to remain unavailable until an order is completed. A refund could happen after a payout. One seller may operate in Germany, another in the United States, while the buyer pays from France.

Then another question appears: who is allowed to receive the money in the first place?

That single transaction can touch payment security, identity verification, anti-money-laundering controls, payouts, refunds, disputes, tax considerations, and potentially regulated payment activities.

For marketplace founders, PCI DSS, KYC, AML, and escrow therefore should not be treated as four compliance boxes to check before launch. They describe different risks inside the movement of money, and each can influence how the product itself needs to work.

The right place to begin is not the checkout page. It is the money flow.

Draw the money before designing the payment screen

Take the simplest transaction your marketplace expects and follow every dollar.

Suppose a customer purchases a service for $500 and the marketplace charges a 10% commission. Several questions immediately appear:

• Who technically accepts the $500 payment?
• Where are the funds held?
• When does the seller become entitled to $450?
• Who receives the marketplace's $50 fee?
• What happens if the customer requests a refund?
• What happens if the seller has already been paid?
• Who handles a chargeback?
• Can the marketplace delay the seller's payout?
• What happens if verification fails after a transaction?
• Which party appears on the customer's statement?

Now repeat the exercise for cancellations, partial refunds, multiple sellers in one order, failed payouts, disputes, promotional credits, and different currencies.

This diagram often reveals more about payment architecture than a list of desired payment methods.

A marketplace is not simply accepting payments. It is coordinating financial relationships between several parties.

3 ways a marketplace can move money

Almost every marketplace payment setup is a variation on one of three structures. Knowing which one you are considering gives both the payment provider and legal counsel a much clearer starting point, because the structure affects who receives funds, how sellers are paid, and where different responsibilities may sit.

1. The marketplace is the merchant of record.

The buyer pays the marketplace, which then manages the financial relationship with the seller. This model gives the platform significant control over the transaction, but it can also create additional responsibilities around payments, refunds, disputes, and the handling of funds.

2. The provider manages the payment flow between the parties.

A regulated payment provider can route payments to seller-linked accounts while allowing the marketplace to collect its commission. The provider handles the underlying payment infrastructure, while the marketplace still needs to define the product logic around onboarding, payouts, refunds, and restrictions.

3. The buyer pays the seller directly.

The marketplace facilitates the relationship without entering the payment flow itself. This reduces the platform’s control over the transaction and can limit its ability to manage commissions, refunds, disputes, or delayed payments through the product.

These are not simply implementation choices. The payment model affects what the marketplace needs from its provider, what the product must support, and which regulatory questions need to be resolved before development begins.

Most of the issues covered below, including escrow-like flows, payouts, chargebacks, and verification, depend on this underlying structure. Defining it on paper before building the payment system makes the rest of the architecture considerably easier to reason about.

Read also: How to Build a Marketplace Website in 15 Steps: The Ultimate Guide

PCI DSS begins with a question: Does your platform need to touch card data?

Founders sometimes hear "PCI compliance" and imagine a certification task that happens near launch.

The architectural decision comes much earlier.

PCI DSS applies to environments that store, process, or transmit payment card account data. What changes with the checkout architecture is the scope of the marketplace’s PCI DSS responsibilities.

For many ecommerce implementations, that difference is reflected in the applicable Self-Assessment Questionnaire:

• SAQ A is intended for eligible merchants that fully outsource account data functions to PCI DSS-compliant third parties.
• SAQ A-EP applies to eligible ecommerce merchants whose websites can affect the security of the payment transaction even though their systems do not electronically store, process, or transmit account data.
• SAQ D covers merchants that do not meet the eligibility criteria for the other SAQ types.

The practical point is that the location and implementation of the payment form can materially change the PCI DSS scope. That decision is therefore part of checkout architecture, not something to consider only before a compliance review.

PCI DSS v4.0.1 also changed an important detail for ecommerce implementations. Since 1 April 2025, merchants using embedded payment pages such as iframes must meet additional SAQ A eligibility criteria related to protection against script-based attacks, or obtain confirmation from the compliant third-party provider that its solution protects the payment page as required. Redirect-based payment flows are treated differently under these criteria.

For a marketplace team, this makes one provider question especially useful before implementation: which SAQ does this specific integration qualify for?

For many marketplaces, the useful architectural objective is straightforward: keep sensitive card data away from the marketplace application wherever the payment model allows it.

A payment provider can handle card collection and return tokens or other references that the application uses for subsequent operations. The marketplace still needs appropriate security and must understand its own PCI DSS responsibilities, but its systems do not necessarily need to become the place where raw card details live.

This distinction affects:

• Checkout architecture.
• Frontend implementation.
• Backend APIs.
• Logging.
• Customer support tools.
• Testing environments.
• Monitoring.
• Incident exposure.

A seemingly harmless debugging decision can undermine the model. If payment request data containing sensitive information starts appearing in application logs, the intended boundary has changed.

Payment compliance therefore needs engineering rules, not just documentation.

Read also: 11 Best Payment Solutions for Online Marketplaces in 2026

KYC is not a signup form

"Verify sellers" sounds like one marketplace feature. In reality, identity verification is a lifecycle.

A seller may submit a legal name, address, date of birth, company information, identification documents, beneficial ownership information, or other details depending on the marketplace, jurisdiction, payment structure, provider, and applicable requirements.

Verification can then produce several outcomes.

The seller may pass immediately. Additional information may be required. Documents may be rejected. Verification may expire or need updating. A business may change owners. A seller previously permitted to receive payouts may become restricted.

That means the marketplace needs states, not simply a verified = true field.

For example:

Not started → Information submitted → Under review → Additional information required → Verified → Restricted

The exact workflow depends on the provider and regulatory context, but the architectural lesson remains the same.

Verification changes over time.

The product needs to know what each state allows the participant to do.

Can an unverified seller publish listings?

Can buyers purchase from them?

Can funds accumulate before verification?

Can payouts begin?

What happens to pending transactions if verification becomes restricted?

Those are product rules with compliance consequences.

Building marketplace payments with multiple parties?

Codica can design payment and verification workflows around how your marketplace actually operates.

Contact us

KYC and AML solve different problems

KYC and AML are frequently mentioned together because identity verification can form part of broader anti-money-laundering controls. They are not interchangeable.

KYC focuses on establishing and verifying information about a customer or business where applicable. AML is broader and can involve assessing risk, monitoring activity, identifying suspicious patterns, sanctions-related controls, recordkeeping, and other measures required under the relevant framework.

For a marketplace founder, the distinction matters because completing identity verification does not automatically answer what should happen after the participant starts transacting.

Consider two sellers. Both successfully complete verification.

Seller A receives twenty relatively ordinary payments over several months.

Seller B suddenly receives a large volume of transactions inconsistent with previous activity, followed by rapid refunds or unusual payout behavior.

Identity verification answers who the participants are to the extent required by the process.

It does not make their future behavior automatically low-risk.

Depending on the marketplace's role, jurisdiction, payment setup, and providers, AML obligations may sit differently across the parties involved. Founders need qualified legal and compliance advice to establish the applicable responsibilities rather than assuming that integrating a KYC vendor transfers every obligation elsewhere.

Technically, however, the marketplace should avoid an architecture that makes risk controls impossible to implement later.

Read also: Building a Custom AI Agent for KYC and AML Automation

Payment providers do more than process cards

Choosing a marketplace payment provider based only on transaction fees can be an expensive mistake. The platform may need far more than checkout.

Marketplace payment infrastructure can potentially involve:

• Connected seller or provider accounts.
• Identity verification.
• Payment splitting.
• Platform commissions.
• Payout scheduling.
• Refunds.
• Chargeback handling.
• Multiple currencies.
• Payout restrictions.
• Tax-related data.
• Reporting and reconciliation.

The exact capabilities and legal structure differ between providers and countries. That is why provider selection should follow the marketplace business model rather than precede it.

A marketplace connecting local tutors with students has a different payment profile from a global B2B marketplace processing high-value equipment transactions. A rental marketplace may need delayed settlement logic. A gig platform may have thousands of small payouts. A marketplace selling physical products may need to divide a single checkout between several merchants.

"Which payment provider should we integrate?" is therefore usually the second question. The first is: "What financial operation does this marketplace actually need to perform?"

Escrow is a legal concept before it is a UX feature

The word "escrow" appears frequently in marketplace product specifications. A typical requirement sounds simple:

"The buyer pays. We hold the money until the job is completed. Then we release it to the seller."

From a user-experience perspective, that resembles escrow. Legally and operationally, the situation can be much more specific.

Holding funds on behalf of other parties can fall within regulated financial activities depending on how the arrangement works and where the marketplace operates. Calling a database balance "escrow" does not make the platform an authorized escrow provider.

For marketplaces operating in the EU, one concept worth discussing explicitly with legal counsel is the commercial agent exclusion under the payment services framework. Whether a marketplace can rely on it depends on the actual relationship between the platform, buyer, and seller, as well as how the money moves through the transaction.

The EU payment-services framework is also evolving through PSD3 and the proposed Payment Services Regulation (PSR). Rather than designing a payment model around an assumed exclusion, founders should confirm the current position for their specific structure before building a flow in which the marketplace receives or controls funds on behalf of other parties.

The architectural question remains straightforward even when the legal answer is not: does the marketplace itself need to control the money, or can the required experience be implemented through regulated payment infrastructure?

This distinction should be resolved before engineers build a custom wallet and start moving real money through it.

Sometimes the required user experience can be implemented using capabilities offered by a regulated payment provider without the marketplace itself taking custody of funds in the way founders initially imagined.

The terminology matters less than the actual flow:

Buyer payment → regulated payment infrastructure → conditions satisfied → seller payout

What matters architecturally is who controls the funds at every stage, under what conditions they can move, and which regulated entity performs the financial activity.

Your database balance is not money

This is one of the easiest marketplace concepts to get wrong. Suppose a seller dashboard displays: Available balance: $1,800. That number is an application record. It does not itself contain $1,800.

The actual funds exist somewhere within the payment infrastructure. Your database records what the marketplace believes the seller is entitled to receive based on transactions, fees, refunds, reserves, payouts, and other events. Those two realities need to remain synchronized.

If the marketplace records a successful payment before the provider confirms it, balances can become inaccurate. If a payout succeeds but a webhook fails, the application may still show funds as available. If events arrive twice and processing is not idempotent, a transaction could theoretically be applied more than once.

Payment architecture therefore needs a reliable financial ledger or equivalent transaction model rather than a balance field that is repeatedly increased and decreased.

Every meaningful change should be explainable.

Why does the seller have $1,800?

The system should be able to reconstruct the answer from transactions rather than trusting the current number alone.

Refunds expose weak payment architecture quickly

The happy path is easy:

Buyer pays → seller delivers → seller receives payout → marketplace keeps commission.

Real marketplaces spend a surprising amount of time outside that path.

A buyer may receive a partial refund. The marketplace may refund its commission but not another fee.

One item in a multi-seller order may be canceled.

A dispute may appear after the seller has already received a payout.

A service may be partially completed.

A payment can succeed while a payout fails.

Each scenario changes who is owed what.

That is why refund logic should be designed alongside payment logic, not added after checkout works.

For every transaction type, founders should know what happens to the buyer amount, marketplace fee, seller entitlement, payment processing costs, and any already completed payout.

If the answer requires someone to manually edit a database balance, the payment model is not finished.

Chargebacks do not respect your marketplace workflow

A marketplace may consider an order complete. The cardholder's bank does not care.

A chargeback can reopen the financial consequences of a transaction after the product workflow appears finished. Depending on the payment setup, somebody needs to absorb the disputed amount and potentially associated fees.

That raises business questions before technical ones:

• Who carries chargeback risk?
• Can seller balances become negative?
• Can future payouts be used to recover an amount?
• Does the marketplace maintain reserves?
• When should a seller be restricted?
• How is evidence collected for disputes?

These policies vary considerably between marketplace models and payment arrangements. The application needs to represent whatever rules actually apply.

A marketplace that models only positive balances and successful payouts may discover too late that money can move backward too.

Chargeback rates also matter at the payment-network level. Under Visa’s Acquirer Monitoring Program (VAMP), the excessive merchant threshold is 150 basis points for the fraud-and-dispute ratio, subject to the program’s applicable event thresholds. That makes dispute monitoring more than an operational dashboard metric: sustained high ratios can trigger additional scrutiny and remediation requirements.

For marketplaces, seller-level tracking remains important even when monitoring also happens at the broader merchant or platform level. A small group of high-risk sellers can materially affect the overall dispute profile, so the system should make those patterns visible before they become a platform-wide problem.

Need more than a basic checkout integration?

Codica can build marketplace payment logic for payouts, refunds, disputes, and complex transaction flows.

Contact us

Webhooks are part of the financial system

Payment providers operate asynchronously. A checkout page redirecting to "success" is not enough to establish the final financial state of a transaction.

Payment confirmation, verification updates, refunds, disputes, payout failures, and account restrictions may all arrive through provider events.

Those events need careful handling.

A robust marketplace should expect that:

• An event can arrive more than once.
• Events may not always arrive in the order expected.
• Processing can fail temporarily.
• A provider may retry delivery.
• Internal services may be unavailable.
• The marketplace may need to reconcile its records later.

Webhook handlers should therefore be idempotent and observable.

The platform should know which event was received, whether it was processed, what internal transaction it affected, and whether intervention is required.

When money is involved, "the webhook probably worked" is not a useful operational state.

Marketplace admin panels need financial controls

Payment architecture eventually reaches the back office.

Operations and support teams need tools to understand what happened without opening the database or asking an engineer to investigate every unusual transaction.

An effective marketplace administration layer may need to show:

• Payment status.
• Seller verification status.
• Marketplace fees.
• Refund history.
• Payout state.
• Disputes.
• Restrictions.
• Provider identifiers.
• Relevant transaction events.
• Failed operations requiring attention.

Permissions become particularly important here.

A support employee who can view payment status does not necessarily need permission to issue a refund. Someone reviewing verification cases may not need access to unrelated customer information. High-impact financial actions may warrant stronger authorization or additional approval.

Admin functionality is part of the payment security model, not merely an internal convenience.

Reconciliation is where your version of money meets reality

Eventually, finance asks a question that the checkout interface cannot answer:

Why does the payment provider show one amount while our marketplace database shows another?

Reconciliation is the process of finding that answer.

Differences can come from fees, refunds, chargebacks, failed payouts, currency conversion, timing, duplicated internal records, missing events, or incorrect transaction states.

As transaction volume increases, manual comparison becomes increasingly unrealistic.

The marketplace needs records that connect internal objects with external payment identifiers and make financial events traceable from beginning to end.

For example:

Order → Payment → Platform fee → Seller entitlement → Refund → Payout

If one link cannot be traced, investigating discrepancies becomes slower.

This is also why financial records should not be casually overwritten when something changes. Preserving transaction history makes it possible to understand how the current state was reached.

Multi-country growth can change the payment model

A marketplace operating in one country may begin with a relatively straightforward setup. Expansion can alter it quickly.

New markets may introduce different payment methods, payout availability, currencies, verification requirements, transfer rules, tax considerations, and regulatory obligations. A payment provider that supports customer checkout in a country may not necessarily support the seller payout model the marketplace requires there.

This is one reason geographic expansion should be reviewed as a payment architecture decision, not merely a localization project.

Before entering another market, founders should verify at least four layers:

1. Can buyers pay using appropriate methods?
2. Can marketplace participants be onboarded and verified?
3. Can sellers or providers receive payouts under the intended model?
4. Can the marketplace legally operate the proposed flow?

A translated interface does not answer any of them.

What we define before building marketplace payments at Codica

Payment development should not begin with a list of API endpoints. At Codica, the useful starting point is the commercial transaction itself.

Marketplace development is a recurring part of Codica’s work. Over 11+ years, Codica has delivered products whose founders have raised more than $56 million. That experience includes marketplace projects across automotive, rental, recruiting, travel, and B2B trade, with payment architecture involving commission logic, split payments, payout scheduling, reconciliation, and escrow-style release conditions.

Who pays whom? When does each party become entitled to funds? What fee does the marketplace earn? When can money move? What can reverse the transaction? Which participant requires verification? What happens when something fails?

From there, the technical model can be defined around the actual business rules.

The review may cover:

• Buyer, seller, and platform money flows.
• Marketplace commission logic.
• Payment provider capabilities.
• Seller onboarding and verification states.
• Payout conditions and schedules.
• Refund and cancellation scenarios.
• Dispute and chargeback handling.
• Transaction and ledger design.
• Webhook processing.
• Admin permissions.
• Reconciliation requirements.
• Geographic expansion plans.
• Security boundaries around payment data.

Legal and compliance specialists still need to determine the exact PCI DSS, KYC, AML, payment-services, escrow, and other regulatory requirements that apply to the specific business.

Engineering then has a different responsibility: make sure the software can actually operate according to those decisions.

The best payment architecture makes exceptional cases ordinary

A successful payment should be boring. So should a refund.

So should a failed payout, a verification request, a duplicate webhook, a seller restriction, and a chargeback.

Not because those events are unimportant, but because the system already knows what each one means.

That is the difference between adding payments to a marketplace and designing marketplace payment infrastructure.

PCI DSS influences how card information should enter and move through the system. KYC affects participant onboarding and access to financial capabilities. AML considerations can extend into ongoing risk controls. Escrow-like flows raise questions about custody and regulated payment activities. Refunds and disputes make financial states reversible. Reconciliation determines whether the platform can explain its own numbers.

None of these belongs exclusively to a compliance document. They eventually become architecture.

For founders, the safest sequence is therefore business model first, regulatory responsibilities second, payment architecture third, and checkout experience after the underlying rules are understood.

Before choosing a payment architecture, map one transaction from start to finish. Use a $500 order and write down who receives the payment, when the seller balance changes, when the platform earns its commission, and when the money becomes available for payout.

Then run the same flow through three less convenient scenarios: a refund after payout, an order involving two sellers, and a chargeback after the seller has withdrawn the funds. If ownership of the money or responsibility for the negative balance becomes unclear at any point, that is a question to resolve with the payment provider or legal counsel before implementation begins.

Codica can turn complex marketplace transaction requirements into practical payment, verification, payout, and administration workflows.

Contact us to discuss the payment architecture behind your marketplace!