kbwenLab

Uniform Invoice Validator

Enter 8 digits to check the Taiwan business number checksum (2023 rule).

Everything runs locally, with a receipt-style workbench and a dot-matrix checksum ladder.

Uses the post-2023 Ministry of Finance rule (divisible by 5) and supports the 7-in-7th-digit special case.

Receipt input

Enter invoice number

Waiting

Only digits are kept while typing, and you can press Enter to validate.

Quick samples

Local only

Every check stays in the browser, which keeps the tool safe for embedded review flows.

Checksum board

Checksum ladder

Monospace dot-matrix layout

Submit an 8-digit value to see each weighted step, split sum, and running total.

How to use

Enter 8 digits and click Validate. The right side shows every weighted step, split-digit sum, and the final verdict.

Common use: double-check invoice forms, vendor records, or pasted spreadsheet rows. Try the "2023-rule only" sample to see a number that passes only under the new ÷5 rule.

Scope: since 2023-04-01 the Ministry of Finance checks the total for divisibility by 5 (was 10); this tool uses the new rule. It only validates format and checksum, and does not verify whether a company actually exists.

Quick guide

Use cases, answers, and nearby tools

Compact below-tool notes that help first-run users and repeated visitors move faster without changing the main interface.

Chinese search: 統編驗證、統一編號檢查、統編檢查碼計算、統一編號是幾碼、統編 8 碼

How to use

Run a clean first pass

  1. Enter an 8-digit business number, or click a sample to load it.
  2. Click validate to see the per-digit checksum ladder and whether it passes (post-2023 ÷5 rule).
  3. Click "2023-rule only" to see a number that is valid under the new rule but rejected by older systems.

Examples

Real jobs this page helps with

  • Invoice header pre-checkConfirm a business number's format and checksum before creating customer records or issuing documents.
  • Debug a false rejectionA customer's number shows invalid in your system? Paste it to see whether it only passes the 2023 ÷5 rule and was blocked by old ÷10 logic.
  • Educational referenceUse the per-digit ladder to explain the weights [1,2,1,2,1,2,4,1] and split-sum logic to colleagues.

FAQ

What people usually want to know

How many digits is a Taiwan business number?

A Taiwan business number (統一編號) is always 8 digits. The last digit is a checksum derived from the others to verify the whole number.

How is the checksum calculated?

Multiply each of the 8 digits by the weights [1,2,1,2,1,2,4,1]; for any two-digit product, add its tens and units; sum the 8 results. The number is valid if the total is divisible by 5.

What changed in the 2023 checksum rule?

Effective 2023-04-01, the Ministry of Finance relaxed the test from "total divisible by 10" to "divisible by 5", so some numbers previously treated as invalid are now valid. This tool uses the new rule.

What is the 7-in-7th-digit special case?

When the 7th digit is 7, the validator also checks whether total + 1 meets the divisibility rule; passing either way counts as valid.

Is this an official lookup?

No. It only does local format and checksum validation in your browser — nothing is uploaded — and it does not confirm the company exists. Use the Ministry of Finance tax portal for existence checks.

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