Nager.EuropeanCommissionVies

A lightweight .NET client for validating European VAT numbers using the official European Commission VIES (VAT Information Exchange System) API.

This library provides simple and strongly typed access to VAT validation including optional qualified checks with trader information.

✨ Features

• Validate VAT numbers via VIES
• Strongly typed request/response models
• Support for qualified VAT checks (trader name, address, company type)
• Async/await support
• CancellationToken support
• Clean and minimal API surface
• Exception-safe argument validation

📦 Installation

Install via NuGet:

dotnet add package Nager.EuropeanCommissionVies

Or via Package Manager:

Install-Package Nager.EuropeanCommissionVies

🚀 Usage

Basic VAT validation

var serviceProvider = new ServiceCollection().AddHttpClient().BuildServiceProvider();
var httpClientFactory = serviceProvider.GetRequiredService<IHttpClientFactory>();

var viesClient = new ViesClient(httpClientFactory);

var response = await viesClient.CheckVatAsync("DE123456789");

if (response != null && response.Valid)
{
    Console.WriteLine("VAT number is valid");
    Console.WriteLine(response.Name);
    Console.WriteLine(response.Address);
}

Check if VAT number is valid (boolean shortcut)

var isValid = await viesClient.IsValidVatAsync("DE123456789");

if (isValid)
{
    Console.WriteLine("Valid VAT number");
}

Qualified VAT validation (with trader details)

var request = new VatCheckRequest
{
    VatNumber = "123456789",
    CountryCode = "DE",
    TraderName = "Example Company",
    TraderStreet = "Example Street 1",
    TraderPostalCode = "10115",
    TraderCity = "Berlin"
};

var response = await viesClient.CheckVatAsync(request);

if (response != null)
{
    Console.WriteLine($"Valid: {response.Valid}");
    Console.WriteLine($"Name match: {response.Name}");
}

Error Codes

Code	Description
MS_MAX_CONCURRENT_REQ	The maximum number of concurrent requests is not linked to a specific IP. It is a global count across all users.

Vat number structure

CountryCode	Example	Abbreviation
AT	ATU9999999p	UID
BE	BE999999999p	N° TVA / BTW-nr. / MwSt.-Nr.
BG	BG99999999p	DDS (ДДС)
CY	CY50999999L	FPA
CZ	CZ901231999p	DIČ
DE	DE99999999p	USt-IdNr.
DK	DK99999999	SE-Nr.

p= Check Digit

https://en.wikipedia.org/wiki/VAT_identification_number

🌍 About VIES

The VAT Information Exchange System (VIES) is operated by the European Commission and allows validation of VAT numbers registered within the European Union.

Official information: https://ec.europa.eu/taxation_customs/vies/

🛠 Requirements

• .NET 10 or later
• Internet connection for VIES API access

📄 License

This project is licensed under the MIT License.

🤝 Contributing

Contributions are welcome. Please open an issue or submit a pull request.