Australia ABN Validation API
Validate Australia ABN numbers via REST API. Backed by ABN Lookup / ABR (real-time) — returns registration status, company name, and address in a single call.
Quick start
CURL
curl -H "Authorization: Bearer YOUR_API_KEY" \ http://localhost:3000/api/v1/validate/AU/51824753556
Single validation
Validate one Australia ABN number. Returns full company details for valid numbers.
const res = await fetch(
'http://localhost:3000/api/v1/validate/AU/51824753556',
{ headers: { 'Authorization': 'Bearer YOUR_API_KEY' } }
);
const data = await res.json();
/*
{
"valid": true,
"status": "active",
"company_name": "Example GmbH",
"address": "Musterstraße 1, Australia",
"country_code": "AU",
"vat_number": "51824753556",
"cached": false,
"request_id": "req_01abc..."
}
*/Response format
{
"valid": true,
"status": "active",
"company_name": "Example Australia Ltd",
"address": "Musterstraße 1, Australia",
"country_code": "AU",
"vat_number": "51824753556",
"cached": false,
"request_id": "req_01abc..."
}| Field | Type | Description |
|---|---|---|
| valid | boolean | true if the number is registered and active |
| status | string | "active", "inactive", "not_found", or "invalid_format" |
| company_name | string | null | Registered company name (where available from authority) |
| address | string | null | Registered address (where available from authority) |
| country_code | string | ISO 2-letter code — always "AU" for this endpoint |
| vat_number | string | The VAT number as sent in the request |
| cached | boolean | true if result served from cache (valid: 24h, invalid: 1h) |
| request_id | string | Unique request ID for support and audit logs |
Batch validation
Validate up to 25 numbers in a single POST request. Numbers are processed in parallel — ideal for onboarding flows and nightly reconciliation.
curl -s -X POST http://localhost:3000/api/v1/validate \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"numbers": [
{ "country": "AU", "vat": "51824753556" },
{ "country": "AU", "vat": "51824753559" }
]
}'[
{
"vat": "51824753556",
"valid": true,
"status": "active",
"company_name": "Example Ltd",
"country_code": "AU",
"cached": false
},
{
"vat": "51824753559",
"valid": false,
"status": "not_found",
"country_code": "AU",
"cached": false
}
]Error codes
| HTTP status | Meaning | Action |
|---|---|---|
| 400 | Bad request — malformed VAT format | Check the VAT format against the pattern below |
| 401 | Missing or invalid API key | Pass a valid Bearer token in the Authorization header |
| 404 | Country not supported | Check /vat-api for the full list of supported countries |
| 422 | Validation failed — invalid format | The number does not match the expected format |
| 429 | Rate limit exceeded | Back off and retry after the Retry-After header value |
| 503 | Upstream authority unavailable | VIES/authority is temporarily down — retry with exponential backoff |
Australia ABN format reference
| Property | Value |
|---|---|
| Country code (ISO) | AU |
| Local name | ABN (Australian Business Number) |
| Format | 11 digits |
| Regex | ^[0-9]{11}$ |
| Example | 51824753556 |
| Standard rate | 10% |
| Validation source | ABN Lookup / ABR (real-time) |
| VIES supported | No |
Australia's GST (Goods and Services Tax) is a flat 10% with no reduced rates. ABN validation is done through the Australian Business Register (ABR) Lookup API. ABNs are 11-digit numbers derived from the ACN (Australian Company Number) with a two-digit prefix.
Frequently asked questions
What does the TaxID API return for a Australia ABN validation?
For a valid Australia ABN number the API returns: `valid: true`, `status: "active"`, plus `company_name` and `address` where available from ABN Lookup / ABR (real-time). For invalid numbers it returns `valid: false` with a reason code. All fields are documented in the API reference.
How fast is the Australia ABN validation API?
Cached results (valid numbers are cached 24h, invalid 1h) respond in under 10ms. Uncached requests that require a live lookup via ABN Lookup / ABR (real-time) typically complete in 100–400ms. The `cached` field in the response tells you whether the result came from cache.
What is the Australia ABN number format?
Australia ABN numbers (ABN (Australian Business Number)) follow the pattern: 11 digits. A valid example is `51824753556`. The TaxID API validates the format locally before making any live request, so malformed numbers fail instantly without consuming your quota.
Can I validate multiple Australia ABN numbers in one request?
Yes. The batch endpoint (POST /api/v1/validate) accepts up to 25 VAT numbers in a single request, processed in parallel. This is ideal for bulk onboarding flows, nightly reconciliation jobs, or importing customer lists. Each item in the response array maps 1-to-1 with your input array.
Start validating Australia ABN numbers
Free plan — 100 validations/month. No credit card required.
Integrate with your stack:
More Australia resources:
Validate VAT in other countries: