The Taiwanese Unified Business Number

The format

A Unified Business Number — 統一編號, usually shortened to 統編 — is eight digits and nothing else. No letters, no prefix on the number itself, no separators. It identifies the business for company registration, for the business tax, and for the government-uniform invoice (統一發票) system all at once, which is why it is the single number a Taiwanese counterparty will give you.

It carries a check digit, and the rule is public:

• ×Multiply the eight digits by 1, 2, 1, 2, 1, 2, 4, 1.
• ΣAdd the digits of each product, not the product itself.
• mod 5The total divides by 5 exactly.

Two things about that rule catch people out. The sum is over the digits of each product, so 2 × 9 = 18 contributes 9 and not 18 — the same idea as a Luhn check. And the modulus is 5, not 10: the Ministry relaxed it in 2023 to widen a range that was running out, and a validator still using the old modulus 10 rejects every number issued since. If the seventh digit is a 7 the number may satisfy the sum either way, which is the one survivor of the older rule.

What the number is, and is not

Being allocated a 統一編號 is being registered as a business in Taiwan. It is not, on its own, proof that a business is currently trading — a dissolved company keeps its number, marked as dissolved, in the same way a cancelled ABN stays in the Australian file.

Taiwan also keeps two registers side by side, and a number belongs to exactly one of them: 公司登記 for companies, and 商業登記 for sole traders and partnerships. They are published as separate datasets with different field names, so a lookup that checks only the first will report a perfectly valid sole trader as unknown. Vatlas asks both.

Finding the company behind the number

The open data platform

The Ministry publishes the registers on data.gcis.nat.gov.tw as a JSON API filtered by the number itself — no key, no quota, no registration. It is the openest register of any country on this site, and it returns the registered name, the registration status, the responsible person, the capital and the seat address in one call.

What the answer contains

A Taiwanese address is published as one string, written largest unit first — city, district, road, number — with no postal code anywhere in the payload and nothing to split it on. Vatlas passes it through whole rather than cutting it on a guess, so address.line1 holds the full address and postalCode and city are null.

There is no legal form field either. In Chinese the form is the tail of the name — 股份有限公司 for a company limited by shares, 有限公司 for a limited company — so it is already in name.

Taiwan-specific pitfalls

• The checksum changed in 2023. Modulus 5, not 10. Libraries that have not been updated reject valid recent numbers.
• Two registers, one number space. A number missing from the company register may be a sole trader in the business register.
• Dates are in the Minguo calendar. 0760221 is 21 February 1987: the year is 1911 behind the Gregorian one. Vatlas converts them.
• A miss is an empty answer, not a 404. The platform returns HTTP 200 with an empty body for a number it does not hold, which naive clients report as an outage.
• No postal code, ever. The register does not publish one.

One API, inside Europe and out

Vatlas turns a business tax number into a company record: legal name, national identifier, legal form, status and address. Same call, same shape, for a 統一編號 and for a French VAT number.

curl "https://api.vatlas.dev/v1/lookup/TW22099131" \
  -H "Authorization: Bearer $VATLAS_KEY"

Response:

200 OK

{
  "data": {
    "vatNumber": "TW22099131",
    "countryCode": "TW",
    "nationalId": "22099131",
    "name": "台灣積體電路製造股份有限公司",
    "legalForm": null,
    "status": "active",
    "address": {
      "line1": "新竹科學園區新竹市力行六路8號",
      "line2": null,
      "postalCode": null,
      "city": null,
      "country": "TW"
    }
  },
  "meta": {
    "source": "GCIS",
    "sourceDate": "2026-09-13"
  }
}

Taiwan is asked live rather than imported, so meta.sourceDate is the day of the call. The shape of the response never changes from one country to the next.

Get a free key Read the documentation

Business numbers in other countries

• Japan
• Singapore
• Israel
• Australia
• France
• All countries

Last updated 13 September 2026.