Microsoft Dynamics GP

Dynamics GP real time EU tax registration number validation using VIES

Tim Wappat

Aug 22, 2013 • 4 min read

Member states of the European Union expose thier VAT (Tax Registration Number) validation to the masses via VIES. Below is an example using Amazon’s VAT registration details against the service on the EU website.

Here the member state to which the organisation belongs has been selected, then the VAT number has been entered allowing for validity check. In the next screen we see the response to clicking the verifty button.

– open data goodness! - now for the cool bit…

Webservice

If you hunt under the FAQ, buried in there, it turns out there is a SOAP webservice available that does the same thing!

http://ec.europa.eu/taxation_customs/vies/checkVatService.wsdl

This WSDL URL is our key to some great functionality for Dynamics GP.

In Visual Studio For Dynamics GP Add-in project create a WCF reference to the VIES SOAP webservice.
In your proxy class you will find checkVatPortTypeClient.CheckVat as a method. This is the one we are after, supply the parameters and by reference the results will be returned

We then create a visual studio add in event handler to fire on the user leaving the Tax Registration field of relevant forms in GP. Hence we can validate the VAT number the user has entered! So in our Add in project in the event handler for the options window Tax Registration Field we handle the event.

Public Shared Sub TaxRegNumberValidateBeforeOriginal(Sender As Object, e As System.ComponentModel.CancelEventArgs)
        Try
            Dim CustomerMaintOptionsForm As MicrosoftDynamicsGpModifiedDictionary.RmCustomerMaintenanceForm.RmCustomerOptionsWindow = _
                                                    MicrosoftDynamicsGpModified.Forms.RmCustomerMaintenance.RmCustomerOptions
            If Not CustomerMaintOptionsForm.TaxRegistrationNumber.IsEmpty Then
                If Windows.Forms.MessageBox.Show("Remember to update address intrastats field too." & vbCrLf & "Do you want to validate this number?", "Validate?", _
                                                 Windows.Forms.MessageBoxButtons.YesNo, Windows.Forms.MessageBoxIcon.Question) = Windows.Forms.DialogResult.Yes Then
                    Using oVATNumberValidationForm As New VATNumberValidation
                        oVATNumberValidationForm.VatNumber = CustomerMaintOptionsForm.TaxRegistrationNumber.Value
                        If oVATNumberValidationForm.ShowDialog() = vbOK Then
                            e.Cancel = True
                        Else
                            e.Cancel = True
                        End If
                        CustomerMaintOptionsForm.TaxRegistrationNumber.Value = oVATNumberValidationForm.VatNumber
                    End Using
                End If
            End If
        Catch ex As Exception
            Windows.Forms.MessageBox.Show("TaxRegNumberValidateBeforeOriginal" & vbCrLf & ex.ToString)
        End Try
    End Sub

Using the address of the company being looked up, we select the state code from the combo box (could automate this), we then supply to the webservice on hitting the validate button. A windows form shows the results of the validation to the user. If the supplied details fail validation we show the windows form to the user so they can correct the issue and try again. On closing the form we update the Tax Registration Field.

Private Sub btnValidate_Click(sender As System.Object, e As System.EventArgs) Handles btnValidate.Click
    If txtVATNumber.Text.Length > 0 And cbxMemberState.SelectedIndex <> -1 Then
        Dim oStringBuilder As New Text.StringBuilder
        Dim o As New VATChecker.checkVatPortTypeClient
        Dim ovalid As Boolean
        Dim oName As String = String.Empty
        Dim oAddress As String = String.Empty
        Dim oResult As String = String.Empty
        Dim oSelectedCountryCode As String = CStr(cbxMemberState.SelectedItem).Split(CChar(("-")))(0)

        oResult = o.checkVat(oSelectedCountryCode, txtVATNumber.Text, ovalid, oName, oAddress)
        If ovalid Then
            oStringBuilder.AppendLine(oName)
            oStringBuilder.AppendLine(oAddress)
            oStringBuilder.AppendLine(oResult)
            txtResults.Text = oStringBuilder.ToString
        Else
            txtResults.Text = "INVALID"
        End If

    Else
        Windows.Forms.MessageBox.Show("Enter VAT number and select member state")
    End If


End Sub

Conclusion

This is a rough example, the webservice call can be asynchronous, the country code derived from addresses, more error checking and neater presentation of the results, window could be derived from Dex windows for familiar Dex styles, however this post is more about what is possible in twenty mins with Dynamics GP plugins and data opened to the world via webservices.

Optionally, if the details of the your company are passed to the service (state & VAT number), then a consultation number is returned which is proof that you have looked up and validated the VAT number should you be challenged on that fact, but this is optional.

Note:

Different countries have maintenance windows where this service will not work check the VIES website for details

Update 15th Oct 2015

Common Errors

Over the years this has been running, the service has some common occasional errors. To handle them, place the following exception handler around the call to the web service (checkvat).

This makes some human readable error messages and makes some sense and instructs the end user as to what to do, preventing helpdesk issues from being logged against these transient errors. This Github project DragonBe VIES has the common errors listed out, I’ve taken my own spin on them below.

Catch ex As System.ServiceModel.FaultException
                    If ex.Message = "GLOBAL_MAX_CONCURRENT_REQ" Then
                        Throw New Exception("The European Commission (EC) VAT Information Exchange System (VIES) has too many requests at the same time to cope with, try again later.", ex)
                    ElseIf ex.Message = "MS_MAX_CONCURRENT_REQ" Then
                        Throw New Exception("The European Commission (EC) VAT Information Exchange System (VIES) has too many requests at the same time to cope with, try again later.", ex)
                    ElseIf ex.Message = "TIMEOUT" Then
                        Throw New Exception("The European Commission (EC) VAT Information Exchange System (VIES) too long to contact member state database, try again later.", ex)
                    ElseIf ex.Message = "SERVICE_UNAVAILABLE" Then
                        Throw New Exception("The European Commission (EC) VAT Information Exchange System (VIES) is currently unavailable, may be undergoing maintenance, try again later.", ex)
                    ElseIf ex.Message = "SERVER_BUSY" Then
                        Throw New Exception("The European Commission (EC) VAT Information Exchange System (VIES) is too busy to service your request, try again later.", ex)
                    ElseIf ex.Message = "MS_UNAVAILABLE" Then
                        Throw New Exception("The European Commission (EC) VAT Information Exchange System (VIES) is currently unable to contact that member state database, try another member state or try this later.", ex)
                    Else
                        Throw
                    End If

                End Try