Turn machine payments into verifiable fiscal events.

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 durable, 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, persists the event, 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, Ed25519-signed fiscal402.receipt/1.0.0, and durable fiscal event history. MPP, AP2, US, UK, and Canada engines are not production.

How can I integrate or verify it?

Start with the integration guide, 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.

Machine payment systems can prove that money moved. Enterprises still need to know what the transaction represented, which jurisdiction applied, which ruleset was used, and whether the evidence can be verified later.

1. PAYMENT SETTLED
2. ↓economic event still unresolved
3. ↓Fiscal402
4. ↓fiscal record

How it works

Settlement first. Fiscal evidence after.

x402 moves value. Fiscal402 observes the settled transfer and makes the event fiscally usable. It does not generate HTTP 402, authorize payment, settle funds, or act as a facilitator.

1. 01

   Settled

   x402 transfer already exists

2. 02

   Observe

   PaymentEvidence, post-settlement

3. 03

   FiscalEvent

   Persist event, parties, provenance

4. 04

   Determine

   EU VAT + engine / ruleset versions

5. 05

   Artifacts

   Exact UBL 2.1 bytes + ledger

6. 06

   Receipt

   fiscal402.receipt/1.0.0

7. 07

   Record

   Query, reconcile, independently verify

System of record

A settlement is temporary. A fiscal record has to survive.

Fiscal402 does not only return a response and forget it. It preserves enough structured evidence to reconstruct how the event was processed.

Reconstructable

Know not just the answer. Know why it was the answer.

Every determination is tied to the event context, evidence sources, engine version and ruleset version used at processing time.

Append-only history

Corrections should create history, not erase it.

Material corrections create new history instead of silently mutating the original record. This is an append-only correction model — not a claim of legal immutability or a blockchain-backed audit log.

EVENT
  │
  ├── determination v1
  │      └── receipt A
  │
  └── correction
         └── determination v2
                └── receipt B

Protocol object

Don't trust the claim. Verify the event.

A Fiscal402 receipt binds the normalized event, fiscal determination and artifacts to a signed payload that can be independently verified. Verification proves cryptographic and structural integrity. It is not a guarantee of tax-authority acceptance.

Trust layer

Verification is local.

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

Integrity

Nothing should disappear between settlement and accounting.

Fiscal402 can identify incomplete or inconsistent fiscal records instead of silently treating them as finished. This is a system capability, not an operator dashboard.

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
• 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 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 model. More rails and jurisdictions over time.

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

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 + durable fiscal history.

Independent dimensions

Protocol is not network. Network is not asset. Asset is not jurisdiction.

Fiscal402 keeps these axes separate so a new payment rail does not rewrite tax, and a new jurisdiction does not rewrite payment ingest.

1. PROTOCOL

   x402

2. ≠ NETWORK

   eip155:1

3. ≠ ASSET

   USDC

4. ≠ JURISDICTION

   NL → DE B2C

Pricing

Free during beta. Standard rate after.

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.

Production

Run Fiscal402 on a real x402 settlement.

If you operate an x402 service selling into Europe, Fiscal402 can turn your settled transactions into durable fiscal records.

Your agents can already pay.Make the transactionfiscally usable.