Skip to content

Fiscal infrastructure for autonomous commerce

Turn machine payments into verifiable fiscal events.

Fiscal402 is post-settlement fiscal infrastructure for autonomous commerce. Fiscal402 turns x402 settlements into EU fiscal determinations, UBL 2.1 accounting artifacts, and cryptographically signed fiscal receipts. Fiscal402 is non-custodial and does not move customer funds.

Join the betaRead the protocol

Non-custodial · Post-settlement · x402 v2 · UBL 2.1 · Ed25519

Two flows. One fiscal event.

At a glance

Five facts, in prose.

Fiscal402 is non-custodial and does not move customer funds. Free during beta at 0 bps. Standard rate after beta is 50 bps (0.5% of fiscalized volume).

What is Fiscal402?

Fiscal402 is post-settlement fiscal infrastructure for autonomous commerce. It turns machine payments into verifiable fiscal events.

Who is it for?

x402 merchants, agent platforms, marketplaces, ERP systems, and accounting workflows that need EU fiscal evidence after a machine payment has already settled.

What problem does it solve?

Settlement proves that value moved. It does not produce a fiscal record. Fiscal402 sits after payment and emits a determination, a UBL 2.1 artifact, and a signed fiscal402.receipt.

What does it support today?

x402 v2 exact on USDC (Base and Ethereum), EU VAT determination, USDC→EUR historical FX, UBL 2.1, and Ed25519-signed fiscal402.receipt/1.0.0. MPP, AP2, US, UK, and Canada engines are not implemented.

How can I integrate or verify it?

Request beta access, POST settled x402 evidence to the Fiscal402 API, then retrieve and independently verify the receipt. Protocol specification and verifier source are public.

Read the about page, the facts table, or the verification model.

Settlement ≠ fiscal record

x402 moves the money.Fiscal402 makes the transaction fiscally usable.

The gap

Payment is not the end of the transaction.

Autonomous systems can pay for APIs, data and compute in seconds. Settlement proves the transfer. It does not produce a fiscal record.

Unresolved transaction

Settlement only

Settlement

amount
1.00 USDC
✓
network
eip155:1
✓
tx
0x4f9c…fd8e
✓

Fiscal context

buyer country
?
buyer type
?
VAT treatment
?
EUR valuation
?
invoice
?
audit evidence
?

How it works

Settlement first. Fiscal evidence after.

Fiscal402 does not generate HTTP 402, authorize payment, settle funds, or act as a facilitator. It observes the settled transfer and produces the fiscal event.

  1. 01

    Request

    Paid resource

  2. 02

    x402

    HTTP 402 + settle

  3. 03

    Settled

    Transfer exists

  4. 04

    Fiscal402

    Observe evidence

  5. 05

    Fiscal event

    EU VAT + artifacts

  6. 06

    Receipt

    fiscal402.receipt

Protocol object

One transaction. One verifiable fiscal event.

fiscal402.receipt binds settlement evidence, fiscal determination and invoice bytes into a single signed object. It is a protocol primitive — not a dashboard.

Fiscal402 receipt

Assembling

Demo example. Illustrates a processed x402 settlement, not a live payment.

Settlement

network
eip155:1
tx
0x4f9c…fd8e
asset
USDC

Determination

regime
OSS_B2C
country
DE
VAT
19%

Artifacts

UBL 2.1
BOUND
ledger
RECORDED

Evidence

signature
Ed25519
UBL SHA-256
MATCH

  • Machine-readable

    fiscal402.receipt / 1.0.0 is the protocol object.

  • Settlement-bound

    Network, transaction hash, asset and amount are recorded as observed.

  • Invoice-bound

    SHA-256 of the exact UBL 2.1 bytes Fiscal402 emitted.

  • Cryptographically signed

    Ed25519 over the canonical payload. JWKS publishes keys.

  • Offline verifiable

    Recompute hashes locally. No Fiscal402 API call is required.

  • Read the protocol →

Trust layer

Don't trust the claim. Verify the event.

Verification is local: receipt, JWKS, optional bound UBL. No Fiscal402 API call is required. VERIFIED denotes cryptographic integrity, not tax-authority approval.

  1. SETTLEMENT
  2. FISCAL DETERMINATION
  3. ARTIFACTS
  4. CANONICAL PAYLOAD
  5. SHA-256
  6. ED25519
  7. RECEIPT
  8. VERIFY

verify

Independent verification does not require a published CLI. The algorithm is the public contract.

Jurisdiction engine

Built for cross-border machine commerce.

The current engine classifies EU VAT for EU-established sellers. Seller country must be an EU-27 member state. Non-EU sellers are not classified.

EU VAT ENGINEFiscal402NLDENLDEFR
  • EU VAT
  • B2B / B2C
  • Reverse charge
  • OSS
  • VIES
  • Historical FX
  • UBL 2.1

Fiscal402 produces technical fiscal classification and evidence. This is not tax advice and not a guarantee of tax-authority acceptance.

Developers

Infrastructure should integrate like infrastructure.

After x402 has settled, submit the evidence. Current public integration is HTTP — typed SDKs are not published on npm.

POST /settlements

POST https://api.fiscal402.com/settlements
Content-Type: application/json
X-Fiscal402-Key: $FISCAL402_API_KEY

{
  "amountUsdc": "1.00",
  "txHash": "0xYOUR_SETTLED_TX",
  "timestamp": "2026-09-10T12:00:00.000Z",
  "payerWallet": "0xPAYER",
  "receiverWallet": "0xPAY_TO",
  "network": "eip155:1",
  "asset": "USDC",
  "scheme": "exact",
  "consumerCountry": "DE"
}

Authenticate ingest with X-Fiscal402-Key. Full walkthrough: Quickstart.

Architecture

One fiscal event primitive. Multiple payment rails over time.

Today Fiscal402 is x402 v2 exact into EU VAT and fiscal402.receipt/1.0.0. Receipt v2 is experimental. UK VAT is an experimental determination path, not a statutory invoice.

  1. x402 v2 exactCurrent
  2. evm-transferLibrary
  3. additional payment protocolsFuture adapter

  1. PaymentAdapter

  2. PaymentEvidence

  3. FiscalEvent

  4. JurisdictionRouter

  5. FiscalDetermination

  6. FiscalArtifact[]

  7. Receipt projection

  8. fiscal402.receipt

  1. EU VATCurrent
  2. UK VATExperimental
  3. additional jurisdiction enginesFuture engine

Payment evidence becomes a fiscal event. Jurisdiction engines then emit a determination. Receipts project that result. Determination is output, not input.

Current production: x402 + EU VAT + receipt v1. UK VAT + receipt v2 is experimental.

Pricing

Free during beta. Standard rate after.

Free beta

0 BPS

Free during beta. Not permanently free.

  • EU fiscal determination for supported flows
  • UBL 2.1 artifacts
  • signed fiscal402.receipt
  • independent verification
  • no setup fee
  • non-custodial architecture
Join the beta

Standard rate after beta

50 BPS

0.5% of fiscalized volume

Commercial billing after beta, agreed with the operator. Not deducted from the x402 transfer. High volume: custom contracted infrastructure pricing.

Custom

High-volume contracted pricing

Pricing policy does not imply settlement-integrated fee collection. Fiscal402 currently operates post-settlement. Native x402 exact splits are not supported. Not tax advice. Not a guarantee of tax-authority acceptance.

Your agents can already pay.Make the transactionfiscally usable.

Join the betaRead the docs
Fiscal402