# Fiscal402 — full public documentation for retrieval

Fiscal402 is post-settlement fiscal infrastructure for autonomous commerce.
Primary description: turn machine payments into verifiable fiscal events.

Canonical website: https://www.fiscal402.com
Canonical API: https://api.fiscal402.com
Canonical GitHub: https://github.com/Fiscal402/Fiscal402

Fiscal402 currently supports x402 v2 exact as its first payment protocol.
Fiscal402 does not settle payments and does not custody customer funds.
Fiscal402 receipts use Ed25519 signatures.
Fiscal402 receipt version 1.0.0 binds the exact UBL UTF-8 artifact using SHA-256.

## Architecture (current production)

x402 v2 exact
→ EU fiscal determination
→ UBL 2.1 / ledger
→ fiscal402.receipt/1.0.0
→ Ed25519 verification

Long-term direction (not live inventory):
payment rails → normalized payment evidence → fiscal event → jurisdiction engine → artifact binding → fiscal402.receipt

## Current capabilities

- Payment protocol: x402 v2 exact, post-settlement
- Custody: none
- Jurisdiction: EU VAT (eu-vat-oss-2026.09)
- VIES: recorded when a buyer VAT ID is supplied for B2B
- FX: USDC → EUR at settled_at only
- Invoice: UBL 2.1, SHA-256 of exact UTF-8 bytes, no XML C14N
- Receipt: fiscal402.receipt / 1.0.0
- Canonicalization: fiscal402.sorted-json/1
- Signature: Ed25519, kid receipt-ed25519-v1, JWKS
- Networks: eip155:8453 (Base), eip155:1 (Ethereum)
- Asset: USDC

## Integration

HTTP is the public integration path.

POST https://api.fiscal402.com/settlements
  Ingest settled x402 evidence. Optional header X-Fiscal402-Key.

GET https://api.fiscal402.com/settlements/{id}
  Fiscal record.

GET https://api.fiscal402.com/settlements/{id}/ubl
  Bound UBL 2.1 XML.

GET https://api.fiscal402.com/v1/receipts/{id}
  fiscal402.receipt

GET https://api.fiscal402.com/.well-known/jwks.json
  Public signing keys.

POST https://api.fiscal402.com/v1/compliance/evaluate
  Sandbox classification. Not tax advice.

POST https://api.fiscal402.com/sandbox/v1/simulate
  Sandbox UBL + receipt. Quota 10/agent/day.

Discovery:
https://api.fiscal402.com/.well-known/fiscal402.json
OpenAPI:
https://api.fiscal402.com/openapi.json

Typed packages such as @fiscal402/node and @fiscal402/express are not published on npm.

## Receipt format overview

spec: fiscal402.receipt
spec_version: 1.0.0 (frozen)
settlement: network, tx_hash, amount_usdc, asset, payer, pay_to, settled_at
determination: regime, tax_category, rate_percent, taxing_country, legal_reference, provenance
fx: eur_per_usdc, as_of, source, net_eur, vat_eur
vies: status and vat_id_hash (never the raw VAT ID)
artifacts: settlement_id, ledger_id, ubl_sha256, ubl_hash_alg
hashes: canonical_payload_sha256, canonicalization
signature: alg=ed25519, key_id, value
disclaimer: not tax advice, not a VAT return, not tax-authority acceptance

Sanitized example:
https://www.fiscal402.com/examples/fiscal402.receipt-1.0.0.json

Verification bundle (synthetic keys, not production):
https://www.fiscal402.com/examples/verify/receipt.json
https://www.fiscal402.com/examples/verify/jwks.json
https://www.fiscal402.com/examples/verify/invoice.xml

## Verification

VERIFIED means cryptographic integrity under Fiscal402 rules.
It does not mean tax-authority approval, legal identity of a wallet, or complete regulatory compliance.

Local verification:
receipt + JWKS + optional UBL
→ recompute fiscal402.sorted-json/1
→ SHA-256
→ Ed25519 over the hex digest
→ optional UBL SHA-256 match

Source-only verifier:
https://github.com/Fiscal402/Fiscal402
Not published to npm.

## Pricing

Free during beta: 0 bps. Not permanently free.
Standard after beta: 50 bps / 0.5% of fiscalized volume.
High volume: custom.
Pricing is commercial policy/accrual. Fiscal402 does not collect fees via x402 split settlement.

## Security model

- Non-custodial
- Post-settlement observation
- Ingest may require X-Fiscal402-Key
- Webhooks: HMAC-SHA256 timestamp.rawBody
- Receipts: Ed25519 + JWKS
- Idempotency: unique(network, txHash)
- Vulnerability reporting: GitHub private advisories on Fiscal402/Fiscal402
- No public security mailbox is published

## Open source boundary

Open: protocol specification, receipt schema, test vectors, verifier source.
Closed: proprietary fiscal execution engine (VAT classification internals, VIES orchestration, FX operations, ingest persistence).

## FAQ

Q: What is Fiscal402?
A: Post-settlement fiscal infrastructure for autonomous commerce. It turns machine payments into verifiable fiscal events.

Q: Does Fiscal402 process payments or hold funds?
A: No. It does not settle, route, split, or custody funds.

Q: Which payment protocols are supported?
A: x402 v2 exact only. MPP is not implemented. AP2 is not implemented.

Q: Does Fiscal402 support EU VAT?
A: Yes, as the first production jurisdiction. Not tax advice.

Q: Does Fiscal402 guarantee tax compliance?
A: No.

Q: Is Fiscal402 free?
A: Free during beta at 0 bps. Standard after beta is 50 bps / 0.5%.

Q: Is Fiscal402 open source?
A: Protocol and verifier source are public. Execution remains proprietary.

Q: How can a merchant integrate?
A: Request beta access, then POST settled x402 evidence to https://api.fiscal402.com/settlements.

## Canonical URLs

https://www.fiscal402.com/
https://www.fiscal402.com/about
https://www.fiscal402.com/facts
https://www.fiscal402.com/docs
https://www.fiscal402.com/protocol
https://www.fiscal402.com/pricing
https://www.fiscal402.com/verify
https://www.fiscal402.com/faq
https://www.fiscal402.com/llms.txt
https://www.fiscal402.com/llms-full.txt
https://api.fiscal402.com/.well-known/fiscal402.json
https://api.fiscal402.com/.well-known/jwks.json
https://api.fiscal402.com/openapi.json
https://github.com/Fiscal402/Fiscal402

Last updated: 2026-09-11