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VAT-exempt business registration is not supported in the Sandbox. If you would like to test value-added tax (VAT) functionality, please file a support request and we can enable your test account as VAT-exempt business.
Before contact Developer Technical Support, please make sure that your User.RegistrationAddress.Country field is correctly set: :
1. login to your sandbox account and change your user address (Home > My eBay > My Account > Addresses) .
2. This can be found in the accounts tab of my eBay. Change to the Country ( other than U.S. and Canada ) of interest and save the settings.
Note. You can make GetUser call and check VATStatus tag returned to determine if the user is VAT-exempted :