What API and data model would support a new Tax workflow for marketplaces

Problem Statement Description

Product context: Stripe is financial infrastructure for internet businesses; its products include payments, Checkout, Billing, Connect, Radar, Issuing, Terminal, and tax tools.

Stripe wants to support a new Tax workflow for marketplaces, where a platform facilitates transactions between buyers and many third-party sellers. The challenge is to define the API surface and underlying data model that allow marketplaces to calculate, collect, attribute, and report taxes correctly across different jurisdictions, seller configurations, buyer locations, product types, and transaction flows.

The primary users are marketplace developers, platform finance/compliance teams, and indirectly the sellers who rely on the platform to handle tax obligations accurately. The workflow must account for marketplace-specific complexity: split payments, connected accounts, seller tax registrations, platform-versus-seller liability, refunds, disputes, exemptions, and reporting requirements across regions.

This is a Technical PM question. Focus on how you would translate product requirements into APIs, objects, data relationships, lifecycle states, and operational guarantees. You do not need to produce production-ready schemas, but you should be clear about what entities exist, how they interact, what events or API calls are needed, and what trade-offs you would make for developer experience, compliance accuracy, and reliability.

The experience should consider:

- Core marketplace tax workflows, including quote/calculation, payment, settlement, refund, and reporting moments.

- API requirements for platforms managing many sellers with different tax registrations, nexus status, exemptions, and product catalogs.

- Data model concepts such as marketplace, seller, buyer, transaction, line item, tax jurisdiction, tax calculation, tax liability, and audit records.

- Integration with payments and connected accounts, including attribution of tax amounts to the right party and handling of split transactions.

- Reliability, idempotency, versioning, auditability, and reconciliation needs for financial and compliance-critical data.

- Privacy and security constraints around seller business data, buyer location data, tax IDs, and cross-border data handling.

- Observability, error handling, webhooks, and operational tooling needed when tax calculations fail, change, or require manual review.

- Rollout and migration considerations for existing marketplace customers adopting the new workflow without disrupting checkout conversion.

Your goal is to frame a clear, developer-friendly API and data model approach that enables marketplaces to manage tax complexity at scale while preserving Stripe-like expectations for reliability, compliance, and ease of integration.