VAT Registration Numbers – a bit of useless information...

John Smith-Daye, Accountant, Essex, MaldonPosted by John Smith-Daye:

As some of you may know, I have a particular affinity towards numbers, rather than words. I would like to take this opportunity to share with you some pretty useless information concerning the arithmetical validity of UK VAT numbers that are issued.

So, let’s consider a hypothetical VAT number (which happens not to be in issue as far as I can tell) – 782237517.

Firstly, it is worth pointing out that UK VAT numbers are all nine digits long – any that are presented to you that do not have this length fall at the first hurdle as they cannot be valid.

A form of “check digit verification” can be used to show by calculation whether or not this number could be valid if issued. Take the first digit, multiply it by 8, the second digit should be multiplied by 7, and so on, until you get to the seventh digit being multiplied by 2. Sub-total the products of all of these calculations, and add the last two digits to that sub-total. The final total thus produced must be divisible exactly by 97 to be capable of being a valid UK VAT number.

Using the example number above:-

7 x 8 = 56

8 x 7 = 56

2 x 6 = 12

2 x 5 = 10

3 x 4 = 12

7 x 3 = 21

5 x 2 = 10

The sub-total of the products is 177. Adding the last two digits, 17, gives a final total of 194 – and bingo! This is exactly divisible by 97, so this number could be valid arithmetically.

(You were warned – this is pretty much a useless bit of information, but, hey, it is quite interesting to number nerds like me).

Alternatively, if you want to check if a VAT number really is valid rather than just arithmetically valid, use the tool provided on the Internet at the following address:-

March 2018


The views expressed in this article are the personal views of the Author and other professionals may express different views. They may not be the views of Lambert Chapman LLP. The material in the article cannot and should not be considered as exhaustive. Professional advice should be sought in connection with any of the issues contained in the article and the implementation of any actions.

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