‍Introduction

The rapid development of artificial intelligence and autonomous systems is reshaping the internet economy. However, one of the main obstacles to achieving fully autonomous AI systems is the lack of a payment system that allows AI agents to operate without human intervention. In May 2025, Coinbase launched x402, which allows APIs and AI agents to transact seamlessly, fostering a more efficient, frictionless, and scalable digital economy for tool usage. In October, the adoption rate of x402 exploded. It processed nearly 500,000 transactions between October 14th and 20th, a 10,780% increase compared to the previous four weeks. It then facilitated over 932,000 transactions between the 21st and 27th, an increase of 34,300% from the previous period, with the growth momentum showing no signs of slowing down.

With its seamless, granular, and open characteristics, x402 poses new challenges to traditional financial and tax logic. Tax authorities urgently need to transform their tax collection and administration models, utilize new tax collection tools, and strengthen international collaboration to effectively implement tax collection on transactions under x402. Based on the logic and characteristics of x402, this article analyzes its challenges to traditional financial and tax logic and proposes financial and tax solutions targeting x402.

1. What is x402?

x402 is an open payment protocol created by Coinbase, which embeds payment functionality directly into the Web structure, reactivating the HTTP 402 (Payment Required) status code to achieve an internet-native, machine-friendly transaction model.

1.1 The x402 Setup

Like the familiar HTTP 404 (Not Found), HTTP 402 is a coding for internet request and response interactions. When the HTTP standard was initially formulated, its designers anticipated that paid resource acquisition might become an important part of the internet in the future, and reserved the HTTP 402 status code for future payment mechanisms. The concept is that the server could respond to a request with, “You must pay before this resource can be provided.” In the current era of surging automation and artificial intelligence, HTTP 402, a code forgotten for over thirty years, has sparked a new wave of enthusiasm in the encrypted AI field.

Based on the HTTP 402 status code, x402 forms a simple and efficient payment framework. The general process is: Buyer requests a resource from the server → [HTTP 402 Response] If payment is required, the server returns the HTTP 402 status code with payment instructions → [Encrypted Signature Authorization] The buyer prepares and submits a payment payload → [On-Chain Settlement] The server uses the x402 coordinator’s /verify and /settle endpoints to verify and settle the payment → If the payment is valid, the server provides the requested content. x402 makes the payment process as natural as loading a webpage.

1.2 The Advantages and Risks of x402

x402 features are seamless, granular, and open. Compared to traditional online payment models, x402 improves the convenience of payment for users. It stitches together the payment and resource delivery steps, eliminating the need for human intervention, reducing transaction costs, and making micropayments and autonomous AI agent transactions possible. At the same time, x402 supports any stablecoin, digital asset, or blockchain, offering great flexibility.

x402 maintains native Web compatibility and is easy to integrate into any HTTP-based service. Video streaming services can leverage x402 to charge per second of content watched, replacing the traditional subscription-based monetization model. Trading AI can retrieve real-time stock market data for $0.02 per request. News websites and research platforms can charge ordinary readers $0.25 per article, allowing pay-on-demand access instead of enforcing monthly subscriptions. x402 provides a payment alternative, offering a completely new toolkit for monetizing network services.

x402 is still in its early stages and is gradually being built into a complete ecosystem. Meanwhile, the security risks associated with x402's rapid expansion are also worth noting. Some views point out that the x402 token has issues like excessive developer permissions and signature replay vulnerabilities, where attackers might use old authorizations to steal funds from wallets. The surge in illicit cross-chain encrypted activities brings significant hidden dangers to crime fighting and tax tracking.

2. How x402 Challenges Traditional Finance and Taxation Logic

Traditional online payments rely on external systems such as credit cards, bank networks, or platform-specific payment processors. These systems are cumbersome to operate, high in system costs, subject to geographical restrictions, and require multiple layers of manual authorization, making them unsuitable for AI-driven transactions. x402 eliminates these obstacles by embedding functionality into the Web structure, offering pay-on-demand, instant transaction completion, and AI-native tokenization (allowing AI agents and human users to pay dynamically without pre-approval or API keys). The characteristics that transcend traditional payment methods bring advantages to x402, while also posing new challenges to traditional financial and tax logic.

2.1 The Missing Trusted Third Party in Seamless Transactions

Traditional payment channels typically use an account model, where both parties to the transaction need to establish a certain level of trust with the participation of a regulated financial institution. Intermediaries such as banks or payment service providers become key nodes for fund clearing and information recording. x402 reduces the intermediate steps of a transaction through on-chain, peer-to-peer settlement, weakening the long-standing power of intermediary participation.

The existing tax system relies heavily on intermediary institutions as trusted compliance nodes. On the one hand, intermediaries bear some reporting obligations, such as banks providing cash flow records based on KYC (Know Your Customer), and payment processing institutions reporting merchant settlement data. On the other hand, intermediaries assist in tax tracking by verifying identity to trace taxable events.

The x402 model isolates third-party intermediaries, losing standardized financial records such as bank statements and payment processor ledgers as verifiable evidence. In x402, the only objective record is the transaction hash on the blockchain. Although the blockchain is publicly transparent and immutable, the technical complexity of smart contract structures and transaction paths, in the absence of mandatory identity binding and transaction reporting obligations, significantly raises the threshold for tax authorities to identify taxable events and reconstruct the real transaction chain. Consequently, tax filing under x402 primarily relies on self-declaration by the taxpayer, supplemented by limited on-chain analysis and risk screening, which to some extent increases the difficulty for tax authorities to identify hidden income and undeclared earnings.

2.2 Fragmentation Risk from Micropayments and Autonomous Machine Transactions

x402 supports micropayments and autonomous AI agent transactions, which may involve multiple blockchains and multiple asset types, further highlighting the problem of tax event fragmentation. Most jurisdictions treat each asset disposal as a taxable event. Even with high-frequency API calls, each payment based on x402 will form an independent on-chain transaction and may be recognized as an independent taxable event. Furthermore, x402 may lead to the separation of tax evidence, such as transaction timing, blockchain, and asset type, leading to further tax evidence fragmentation on top of tax event fragmentation. Without adjusting the existing taxation logic, x402 may lead to a geometric increase in the number of taxable events and significantly push up the technical difficulty of tax collection and administration.

2.3 The Challenge of Taxpayer Identification Across Multiple Chains and Assets

x402 supports any stablecoin, digital asset, or blockchain. x402's openness to various blockchains and crypto-assets amplifies the challenge that blockchains and crypto-assets pose to traditional financial and tax logic. This challenge is specifically manifested as the issue of tax jurisdiction under borderless transactions and the issue of tax tracking under payment anonymity.

Regarding the issue of tax jurisdiction under borderless transactions, the location principle is an important basis for the existing tax system to determine the taxpayer's tax location and tax jurisdiction. However, multi-chain settlement under x402 involves multiple locations of economic activity, which may lead to an inability to identify the tax location. This makes it difficult to define the tax attribution of transactions, potentially resulting in tax overlaps and tax vacuums.

Regarding the issue of tax tracking under payment anonymity, the anonymity under x402 is not just the anonymity of encryption, but an anonymity that is both structural and automated, generated based on multi-chain, programmable, and decentralized settlement standards. x402's AI-driven routing, self-custody identity layer, and off-chain storage of metadata all jointly strengthen information privacy protection, weakening the ability of tax authorities to obtain complete transaction information through traditional financial intermediaries and centralized platforms, thus posing a substantial challenge to tax collection models centered on third-party reporting.

3. Financial and Tax Solutions for x402

To address the challenges posed by x402, tax collection and administration need to keep pace with x402, implementing effective regulation targeting its seamless, granular, and open characteristics.

3.1 New Anchor Points for Obtaining Taxpayer Information

x402 simplifies the payment process and weakens the role of traditional banks, payment institutions, and other intermediaries as anchor points in the tax information chain. To maintain the availability and reliability of tax information, tax authorities need to establish new information "anchor points" and trust mechanisms within the x402 system.

One possible approach is to embed standardized tax metadata into x402, incorporating tax regulation into the seamless structure of x402. This would require x402 payment requests and payment proofs to include structured fields such as the merchant's VAT number, invoice number, and the hashed value of the payer's tax identification number, to ensure the reliability and traceability of tax information and establish an anchor point for tax identification.

Furthermore, from the perspective of keeping the x402 core protocol lightweight, externalized paths for obtaining tax information can also be explored: without modifying the core settlement logic, structured tax data can be carried by auxiliary files or parallel data channels, and cryptographically linked to specific x402 transactions via hash values, thereby extending the tax information functionality in a "sidecar" manner.

3.2 New Ways to Manage Taxable Events

For the management of taxable events, in the scenario where x402 may lead to a significant increase in the number of taxable events, tax authorities need to consider adjusting existing collection and administration models and gradually introducing adaptable collection tools.

In terms of the collection and administration model, continuing to levy taxes on a transaction-by-transaction basis would lead to excessively high compliance and management costs in the context of highly fragmented taxable events. Tax authorities can explore models of net settlement or regular batch taxation, aggregating taxable events generated in micropayment scenarios on a monthly or quarterly basis. Specifically, a tax settlement layer can be designed above the x402 payment layer to collect and categorize original transaction events by dimensions such as tax jurisdiction and tax type, calculating the net taxable amount for each tax period. Compared to transaction-by-transaction reporting, this model is expected to reduce the reporting burden for taxpayers and tax authorities and lower collection costs, while ensuring tax neutrality and fairness.

In terms of collection tools, the role of data analysis tools such as artificial intelligence can be further leveraged to assume the function of automated identification and risk monitoring for high-frequency, fragmented transactions. On the one hand, machine learning technology can be used to cluster and classify different transaction patterns, assisting tax authorities in understanding new types of taxable behavior under x402. On the other hand, fragments that may constitute taxable events can be automatically extracted from the continuous transaction flow and pre-filled tax reports can be generated for random inspection and review by tax personnel.

3.3 Strengthening International Cooperation to Form New Rules

For the coordination of tax jurisdiction, in the context of x402 transactions being highly cross-border and de-territorialized, jurisdictions' understanding of tax ownership and the application of rules can easily diverge. To reduce double taxation and tax vacuums, it is necessary to strengthen communication and cooperation through international organizations and bilateral/multilateral arrangements to form a set of basic principles for tax jurisdiction and conflict resolution mechanisms applicable to the x402 scenario. This will provide a unified framework for the tax jurisdiction of x402 transactions, clearly defining tax attribution while respecting the differences in national tax systems. At the same time, in the context of fragmented tax data, it is necessary to explore the establishment of cross-border tax information-sharing arrangements related to x402, supporting cross-border tracking and cross-border reconciliation while complying with statutory confidentiality and data protection requirements.

For targeted collection and administration of x402, the key is to fully understand the technical logic of x402 and, on this basis, appropriately transform its programmable elements into regulatory tools. To achieve a balance between payment innovation and tax collection and administration, a relatively ideal approach is to integrate some tax identification, declaration, and information recording functions into the x402 structure through standardized interfaces or modules. This aims to technically achieve the maximum possible seamless connection between the payment process, business content response, and tax collection, reserving space for embedding finance and tax compliance at the protocol layer.

4. Conclusion

x402 creates a new paradigm for internet-native payments. Its seamless, granular, and open characteristics are rewriting traditional financial and tax logic, while also bringing about numerous difficulties such as a lack of transparency in financial and tax information and fragmentation of tax data. Tax authorities urgently need to keep up with industry developments and proactively plan an AI-driven x402 tax collection, administration, and compliance new system to ensure tax security.