HeyNineteen.VatNumber

A library for validating and creating instances of Uk VAT numbers in a type safe manner.

Based on information at:

• https://en.wikipedia.org/wiki/VAT_identification_number
• https://discover.hubpages.com/business/Check-VAT-Numbers-UK

The library is capable of parsing string representations of the 4 types of VAT numbers used in the UK:

• standard: 9 digits (block of 3, block of 4, block of 2 – e.g. GB999 9999 73)
• branch traders: 12 digits (as for 9 digits, followed by a block of 3 digits)
• government departments: the letters GD then 3 digits from 000 to 499 (e.g. GBGD001)
• health authorities: the letters HA then 3 digits from 500 to 999 (e.g. GBHA599)

(Source: https://en.wikipedia.org/wiki/VAT_identification_number)

Once parsed, a UkVatNumber exposes the following properties

• ShortFormat e.g. "123456783", "123456783123", "001"
• LongFormat e.g. "GB123456783", "GB123456783123", "GBGD001"
• EuCompatibleFormat e.g. "GB888800181"
• CheckDigitType - the method used to calculate the check digits in the number. Either Modulos97 or Modulos9755
• VatNumberType - either Standard, BranchTrader, GovernmentDepartment, HealthAuthority.

Usage/Examples

Check validity

var vatNumber = "123456783";
var result = UkVatNumber.Validate("123456783");

if(result.IsSuccess)
{
    Console.WriteLine($"'{vatNumber}' is a valid Uk Vat number.");
}
else
{
    Console.WriteLine($"'{vatNumber}' is not a valid Uk Vat number. {result.Message}");
}

Create an instance

var vatNumber = "123456783";
var result = UkVatNumber.Parse("123456783");

if(result.IsSuccess)
{
    Console.WriteLine($"'{vatNumber}' is a valid Uk Vat number.");

    var instance = result.Value;
    Console.WriteLIne($"Short format: {instance.ShortFormat}");
    Console.WriteLIne($"Long format: {instance.LongFormat}");
    Console.WriteLIne($"EU compatible format: {instance.EuCompatibleFormat}");
    Console.WriteLIne($"Type: {instance.VatNumberType.Name}");
    Console.WriteLIne($"Check digit type: {instance.CheckDigitType.Name}");
}
else
{
    Console.WriteLine($"'{vatNumber}' is not a valid Uk Vat number. {result.Message}");
}