Getting started · 🇦🇹 Austria - OpenFiskal Platform API

This guide walks the v1 integration contract for Austria. You create an aut API key, onboard a merchant with an Austrian fiscal_identity, register a location and terminal, fiscalize the register under RKSV, open a register session, start an operation, and complete it with the typed payment contract.

Examples use https://sandbox.api.openfiskal.com/v1. Replace with https://api.openfiskal.com/v1 when you go live.

Register fiscalization on the public API today is only supported for DE / KassenSichV. Calling POST /registers/{id}/fiscalize on an Austrian location currently returns 422 validation_error. Austrian RKSV fiscalization is rolling out — contact support@openfiskal.com for current AT enablement status before scheduling go-live. The merchant, location, and register data shapes shown here are stable and safe to integrate against now; the fiscalize step and the RKSV fiscal_information payload are the parts that activate when AT is enabled for your tenant.

Prerequisites

An OpenFiskal tenant
A tenant-scoped, country-scoped API key (of_test_aut_… or of_live_aut_…)
curl or an HTTP client
A backend service / database to store your API key, entity IDs and ETags

Authentication model

Use the standard bearer header on every request. The key encodes the environment and country — of_test_aut_… for the Austrian sandbox, of_live_aut_… for Austrian production. An aut key rejects payloads for any other country.

-H "Authorization: Bearer of_live_aut_abc123..."

Every merchant-scoped request must also include:

-H "X-OpenFiskal-Merchant: merchant_01HXYZ"

This header value is the merchant ID returned by POST /merchants, not your API key.

Create resources

Create these resources in order. The register cannot fiscalize until the merchant has an AUT fiscal_identity.

Create your API key

Generate an aut key at console.openfiskal.com. Store it in your secrets manager. Format: of_{env}_aut_{random}, e.g. of_test_aut_abcdefgh12345678.

Create a merchant

country_code and every address.country_code must be AUT (ISO 3166-1 alpha-3). The Austrian fiscal_identity requires legal_entity_id_type (one of VAT_ID, TAX_ID, GLN). Provide the corresponding identifier — vat_id (UID, e.g. ATU12345678), tax_number (Steuernummer), or gln (13-digit Global Location Number).

curl -X POST https://sandbox.api.openfiskal.com/v1/merchants \
  -H "Authorization: Bearer of_test_aut_abc123..." \
  -H "Content-Type: application/json" \
  -d '{
    "legal_name": "Alpenblick Handels GmbH",
    "country_code": "AUT",
    "address": {
      "line1": "Mariahilfer Straße 24",
      "city": "Wien",
      "postal_code": "1070",
      "country_code": "AUT"
    },
    "fiscal_identities": [
      {
        "country_code": "AUT",
        "legal_entity_id_type": "VAT_ID",
        "vat_id": "ATU12345678"
      }
    ]
  }'

The returned id becomes the X-OpenFiskal-Merchant header on every merchant-scoped request that follows.

Create a location

A location is a physical point of sale. timezone is a required IANA zone string.

curl -X POST https://sandbox.api.openfiskal.com/v1/locations \
  -H "Authorization: Bearer of_test_aut_abc123..." \
  -H "X-OpenFiskal-Merchant: merchant_01HXYZ" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Wien Neubau",
    "address": {
      "line1": "Mariahilfer Straße 24",
      "city": "Wien",
      "postal_code": "1070",
      "country_code": "AUT"
    },
    "timezone": "Europe/Vienna"
  }'

Create a register

A register is the logical checkout (Registrierkasse) that creates operations.

curl -X POST https://sandbox.api.openfiskal.com/v1/registers \
  -H "Authorization: Bearer of_test_aut_abc123..." \
  -H "X-OpenFiskal-Merchant: merchant_01HXYZ" \
  -H "Content-Type: application/json" \
  -d '{
    "location_id": "loc_01HXYZ",
    "name": "Kassa 1",
    "external_id": "pos-register-1"
  }'

Fiscalize the register (rolling out)

Once enabled for AT, POST /registers/{id}/fiscalize provisions the RKSV components — the SCU and Registrierkasse — using the merchant’s AUT fiscal_identity and the location’s country. The response is 202 Accepted; poll GET /registers/{id} until fiscalization_status is "fiscalized" (the timestamp is fiscalization.fiscalized_at). Until AT is enabled for your tenant this call returns 422 validation_error.

curl -X POST https://sandbox.api.openfiskal.com/v1/registers/reg_01HXYZ/fiscalize \
  -H "Authorization: Bearer of_test_aut_abc123..." \
  -H "X-OpenFiskal-Merchant: merchant_01HXYZ"

Verify your saved IDs

Persist the returned merchant, location, and register IDs. You will use them for every later operation request.

Perform a fiscalized sale

Once your register is fiscalized, you can create and complete sale operations. The request body is identical to other countries; the response’s fiscal_information carries the RKSV-specific shape.

Open a session

Every POS sale, return, or exchange must bind to an open register session. Send a session_open operation with the register, currency, and counted opening cash float. Without an open session, POST /operations with source: POS is rejected.

curl -X POST https://sandbox.api.openfiskal.com/v1/operations \
  -H "Authorization: Bearer of_test_aut_abc123..." \
  -H "X-OpenFiskal-Merchant: merchant_01HXYZ" \
  -H "Idempotency-Key: ses-2026-04-30-reg_01HXYZ-open" \
  -H "Content-Type: application/json" \
  -d '{
    "type": "session_open",
    "register_id": "reg_01HXYZ",
    "currency": "EUR",
    "opening_balance_amount": "50.00"
  }'

Persist the returned session_id. See Sessions for cash adjustments, end-of-shift counting, and closing.

Start an operation

POST /operations is a single-shot create. All monetary fields are decimal strings, not integers. pretax_amount + tax_amount + tip_amount must equal total_amount. line_items is required with at least one entry.

curl -X POST https://sandbox.api.openfiskal.com/v1/operations \
  -H "Authorization: Bearer of_test_aut_abc123..." \
  -H "X-OpenFiskal-Merchant: merchant_01HXYZ" \
  -H "Idempotency-Key: op-order-1001-start" \
  -H "Content-Type: application/json" \
  -d '{
    "register_id": "reg_01HXYZ",
    "source": "POS",
    "type": "sale",
    "currency": "EUR",
    "external_id": "order-1001",
    "pretax_amount": "39.72",
    "tax_amount": "2.78",
    "tip_amount": "0.00",
    "total_amount": "42.50",
    "line_items": [
      {
        "title": "Mittagsmenü",
        "sku_identifier": "MENU-LUNCH",
        "quantity": 1,
        "unit_price": "42.50",
        "total_amount": "42.50",
        "taxes": [
          { "name": "USt. 10%", "rate": "0.10", "tax_amount": "2.78" }
        ]
      }
    ]
  }'

Always send line_items[].taxes[].

Complete the operation

Completion includes typed payment legs. Use one entry per tender leg and include processor references where available. Send the latest ETag in If-Match. The completed operation returns fiscal_information with the RKSV regime.

curl -X POST https://sandbox.api.openfiskal.com/v1/operations/op_01HXYZ/complete \
  -H "Authorization: Bearer of_test_aut_abc123..." \
  -H "X-OpenFiskal-Merchant: merchant_01HXYZ" \
  -H "Idempotency-Key: op-order-1001-complete" \
  -H 'If-Match: "1"' \
  -H "Content-Type: application/json" \
  -d '{
    "payments": [
      {
        "payment_id": "pay_1001_card",
        "method": "card",
        "amount": "42.50",
        "currency": "EUR",
        "status": "captured",
        "processor": "sumup",
        "card_brand": "visa",
        "processor_reference": "ch_123",
        "processed_at": "2026-02-26T12:05:00Z"
      }
    ]
  }'

Response:

HTTP/1.1 200 OK
ETag: "2"
X-Request-Id: req_01JCOMPLETE

{
  "id": "op_01HXYZ",
  "resource_version": 2,
  "status": "completed",
  "payments": [
    {
      "payment_id": "pay_1001_card",
      "method": "card",
      "amount": "42.50",
      "currency": "EUR",
      "status": "captured",
      "processor": "sumup",
      "processor_reference": "ch_123",
      "card_brand": "visa",
      "processed_at": "2026-02-26T12:05:00Z"
    }
  ],
  "fiscal_information": {
    "regime": "RKSV",
    "document_number": "2026-000123",
    "document_type": "Beleg",
    "transmitted_at": "2026-02-26T12:05:01Z",
    "cashbox_id": "cashbox-01HXYZ",
    "certificate_serial": "1A2B3C4D5E6F",
    "signature": {
      "signed_at": "2026-02-26T12:05:00Z",
      "transaction_counter": 4822,
      "turnover_counter": "12345.67",
      "signature": "base64encodedSignature==",
      "certificate_serial": "1A2B3C4D5E6F"
    },
    "verification": {
      "qr_data": "_R1-AT0_cashbox-01HXYZ_4822_2026-02-26T12:05:00_42.50_0.00_0.00_0.00_0.00_..."
    }
  }
}

Void an open operation

If the sale is abandoned before completion, void the open operation:

curl -X POST https://sandbox.api.openfiskal.com/v1/operations/op_01HXYZ/void \
  -H "Authorization: Bearer of_test_aut_abc123..." \
  -H "X-OpenFiskal-Merchant: merchant_01HXYZ" \
  -H "Idempotency-Key: op-order-1001-void" \
  -H 'If-Match: "1"' \
  -H "Content-Type: application/json" \
  -d '{ "reason": "void_before_completion" }'

Next steps

Transaction lifecycle — operation lifecycle in detail
Payment lifecycle — split tender, asynchronous settlement

Overview

Transaction processing

Operations and delivery

Fiscalization API

Changelog

Getting started · 🇦🇹 Austria

Prerequisites

Authentication model

Create resources

Perform a fiscalized sale

Void an open operation

Next steps

​Prerequisites

​Authentication model

​Create resources

​Perform a fiscalized sale

​Void an open operation

​Next steps

Prerequisites

Authentication model

Create resources

Perform a fiscalized sale

Void an open operation

Next steps