Home Unified Business Number Taiwan
Taiwan Unified Business Number validator
How the Unified Business Number format works
- Format
- 8 digits with a weighted digit-sum check (the total must be divisible by 5)
- Example
- 22099131
Things to watch for
- Since April 2023 the check total only needs to be divisible by 5 (it used to be 10) — validators still using the old rule wrongly reject newly issued numbers
- When the 7th digit is 7, its weighted product (28) can count as either 1 or 0, so two totals are accepted
- Checksum only — a pass doesn't confirm the business is registered or currently operating
^[0-9]{8}$A Unified Business Number (統一編號, often shortened to 統編) is the 8-digit identifier Taiwan assigns to companies, businesses and other organisations. When the buyer is a business, its UBN is printed on the uniform invoice (統一發票). Because the number ties invoices and filings to the right business, one wrong digit can send a tax document to the wrong party. The check calculation is there to catch errors like that.
How the check works
Multiply the eight digits by the weights 1, 2, 1, 2, 1, 2, 4, 1. Then add up the individual digits of each product rather than the products themselves, so a product of 18 contributes 1 + 8 = 9. This step is easy to miss. For the example 22099131, the products are 2, 4, 0, 18, 9, 2, 12, 1 and their digits add up to 30. That total must be divisible by 5. If the 7th digit is 7, its product of 28 can be read two ways, so the tool tries both totals.
Why the rule changed from 10 to 5
Until April 2023 the total had to be divisible by 10. Taiwan’s Ministry of Finance relaxed the rule to divisible by 5 and asked agencies to update their checking programs by 31 March 2023. That roughly doubles the number of 8-digit combinations that pass, which is why validators still applying the old rule reject some genuine new numbers. The change is backward-compatible: any multiple of 10 is also a multiple of 5, so every number that passed before still passes.
What a pass doesn’t tell you
A pass means the digits are internally consistent. It doesn’t show that the number has been issued, that the business is still operating, or which business it belongs to. The commerce registry is the authority for that.
Scope: Taiwan UBN format and checksum validation only. It doesn’t cover business-registration status.
Content last reviewed 2026-10-11.
Unified Business Number FAQ
Why does an older validator reject a new Taiwan UBN?
It's probably still using the pre-2023 rule. Since April 2023 the weighted digit total only has to be divisible by 5, not 10, so some newly issued numbers fail older code. This tool applies the current rule, which also accepts every number that passed the old one.
What is the special case for the 7th digit?
The 7th digit has a weight of 4, so a 7 in that position produces 28. Its digits add up to 10, which can be counted either as 1 (1 + 0) or as 0. This tool tries both readings and accepts the UBN if either total is divisible by 5.
Is a UBN the same as a Taiwan National ID number?
No. The National ID (身分證字號) identifies an individual and is a letter followed by 9 digits. The UBN is an all-numeric 8-digit identifier for businesses and organisations, and it uses a different check calculation.