Before revision: Therefore, when the VIES validation returns a negative result, only the validation at the national level of the VAT taxpayer status of a NIP number may decisively clarify its validity as a VAT taxpayer (status check available freely at ).
After revision: Therefore, when the VIES validation returns a negative result, only the validation at the national level of the valid VAT numer status of a NIP number may decisively clarify its validity as a VAT taxpayer (status check available freely at ).