Checks whether a Korean business or corporate registration number is structurally valid using its check digit. It also reads the business type out of the number.

How to use it

1. Type the number (hyphens optional)
2. See whether the format checks out
3. See what class of business the number belongs to

Common questions

Can it tell me whether the number is really registered?

No. It only checks that the last digit matches what the earlier digits compute to. Whether a Korean business registration number actually exists has to be looked up with the National Tax Service.

Then what is it good for?

It catches typos. One wrong digit breaks the calculation, so you can spot it before sending a lookup.

What do the two middle digits mean?

The type of business. 01–79 is an individual taxable business, 81–88 the head office of a for-profit corporation, 90–99 an individual tax-exempt business, and so on.

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