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ID Validation: Frequently Asked Questions

Important Notes

If you notice that an entry is outdated, please let us know.

If errors occur, please also always check the configuration again, especially the separator for CSV files and the encoding for the other file formats (UTF-8 or Win1252). This was one of the most common causes of errors in the past. Check this parameter in conjunction with batch processing and background processing (command line interface).

ID Validation

Do I need to purchase a license for each user?

The VAT Validation is not limited to a number of users. You can distribute the program for any number of users in your company. One license is valid for one company location (VAT ID number dependent).

Can I upgrade to a higher version with a license?

If you have purchased an annual license, you can update to any new version. The main license allows an update only within the main version. When a new main version is released, it is necessary to purchase an update.

Are individual program customizations possible?

Yes. We will be happy to review your requirements for this in order to present you with the best possible solution. Contact us!

Do I need to unlock additional URLs (proxy server)?

If you have problems with the connection, please check if you have access to the following URLs or domains:


We only use these URLs for communication.

VAT Validation

Why do we get: “Unable to connect to the server (result 999)”?

If you are already using version 2.3.1 or higher and receive this return code, this may be due to a configuration that has not been updated. This can be corrected in a simple way via the following way:

Activate the debug mode via “Menu Extra - Debug Mode” and then open the settings and switch to the “Debug” tab. The BasicUrl set in it should be listed in it with the value:

BZSt interface URL

FAQ ‘VAT Validation’

After saving the change, error 999 should be fixed.

What is the difference between the validation on the BZSt website and the VAT Validation?

There is no difference between the online query and the check by the VAT Validation with regard to the result of the query or confirmation of a USt-IdNr. The program calls the public interface of the Federal Central Tax Office (BZSt) for each transferred USt-Id number and returns the answer either at the interface in the program or in the corresponding export file. Only communication errors with the servers of the BZSt are output as additional error messages. You can therefore be sure that the results at the time of the check correspond to a direct online query.

I get wrong results! Why?

It happens time and again that an audit returns data that shows a VAT ID number as invalid, and this has been the case for weeks or even months (valid-to value). The cause is partly attributable to the processing speed of the offices responsible. Depending on the status of the data used for the check, an already invalid VAT registration number may be returned as valid. Unfortunately, we have no access to or influence on this data.

Why should I check the VAT number already validated at regular intervals?

For example, a VAT number that has been confirmed as valid may be declared invalid after the customer has moved, unless you receive the corresponding change of address. Insolvencies or mergers can also cause a VAT number to become invalid overnight. To prevent this, it is advisable to check your VAT registration numbers at regular intervals. Using the filter settings, you will only be informed of invalid VAT registration numbers so that you do not lose track of them.

Why do I get a message that I can’t connect?

In the past, this message was usually triggered by maintenance work of the German Federal Central Tax Office. erpware is aware of this problem and is trying to develop an automatism here to integrate this information into the VAT Validation as well.

Why does it take a long time to validation a VAT ID?

There are several components behind the process of checking the VAT ID number that can contribute to a delay. Starting from your own network infrastructure (proxy server, if applicable) to the internal forwarding at the Federal Central Tax Office (BZSt) to other credit agencies. Maintenance work on the BZSt system may also be partly responsible.