If you’ve been given a 15-digit China business registration number, you may be wondering how you can go about verifying it.

That’s certainly possible, but you might not be aware that you can also get quite a lot of information from a China business registration number simply by knowing how to break it down.

## 15-Digit China Business Registration Number Overview

When a business is registered in China, it goes to the AIC and gets a registration number on its business license. The registration number is currently 15 digits long, and can be broken down into the following parts:

**First 6 digits: registering authority****Next 8 digits: sequencing number****Final digit: check digit**

That gives you a breakdown like this:

XXXXXXXXXXXXXXX(six digits)(eight digits)(final digit)Registering authoritySequencing numberCheck digit

Now let’s look at how those sections work in detail.

## First 6 Digits: Registering Authority

The first six digits of the China business registration number are the code of the registering authority and you can use this to determine the location of this registration.

## Next 8 Digits: Sequencing Number

The next 8 digits in the registration number are described in official documentation as the 顺序码 – “sequencing number”. You can get some information from the first of these 8 digits:

- The sequencing number of domestic companies begins with 0, 1, 2 or 3;
- Foreign-invested companies start with a 4 or 5;
- Individual business registrations start with 6, 7, 8 or 9.

To clarify: this is the first digit of the *sequencing number*, not the whole registration number.

The sequencing number is unique for the registering authority that gave it. It is possible, though, that companies in different jurisdictions could have the same sequencing number. In that case, their registration numbers would be differentiated by the registering authority (first six digits) and check digit (final digit).

## Final Digit: The Check Digit

The check digit allows quick sanity checks on the China business registration number. If something in the number has been mistyped, the check digit will compute differently in most cases. This makes it easier to spot invalid numbers, especially when processed by a computer.

Note that the check digit does little to nothing to prevent fraudulent numbers, because a fraudster can easily calculate the ‘correct’ check digit for a registration number they have made up. It might make it possible to spot lazy or incompetent scammers, but the most likely scenario with fraudulent registration numbers is that the scammer has simply taken a real registration number from a legitimate company, so the check digit would reveal nothing.

The check digit is calculated using an algorithm called **GB/T 17710-1999**. This is also known as the mod 11, 10 algorithm (ISO 7064). You can validate or calculate this as follows:

*n*is the length of the number (how many digits) including the check digit (the check digit is an).*j*is an index of the positions in the number starting from the left (so when j=n we’re on the rightmost digit).

Go through the number from left to right calculating an intermediate result Tj for each position, using this equation:

Tj = ((Tj-1 + an-j+1)||10 * 2)|11

To break that down:

- Get the value of T for the previous position.
- Add it the digit j-1 positions from the right.
- Get the remainder of that sum divided by 11.
- If that remainder is 0, use 10, otherwise use that remainder.
- Multiply that remainder (or 10) by 2.
- Get the remainder of that product divided by 11.

Because Tj-1 doesn’t exist for the first digit, you use T0 = 10. Having recursively calculated Tj for each position in the number, **the check digit is calculated** by:

an = (11 – Tn-1)|10

To break that down:

- Get the value of T for the penultimate digit (the check digit will be the final digit an).
- Subtract that value from 11.
- Get the remainder of that divided by 10.

You can **validate a given check digit an** (i.e. check that the number has probably been written correctly) with this calculation:

(Tn-1-1 + an)||10

If that calculates to 1, then the number has probably been written correctly.

## Other Features of the 15-Digit China Business Registration Number

The official documentation on the 15-digit China business registration number also lists some other requirements and features for them:

- They are unique at a national level
- There is no meaning in the number [e.g., a higher number does not suggest anything about a company]
- They do not change
- They are not transferable
- Even if the number of the registering authority changes, existing registration numbers are not permitted to change. Only new registrations will get the new authority number

## Phasing Out of the 15-Digit China Business Registration Number

Since 1st October 2015 China has commenced implementation of a new China business registration number system and in the future all companies will have an 18-digit registration number.

This system is being rolled out over a period of 2 years, and the 15-digit number will cease to be used at the end of 2017.