Is it possible to deduct VAT on a transaction that conflicts with the national civil code?

In C-114/22. Polish case the tax authority denied the buyer’s right to deduct VAT, saying that – although the buyer accepted and paid the invoice – the transaction in question is void based on the Polish Civil Code.

During its preliminary ruling, the European Court stated: the right to deduct VAT is an immanent part of the VAT system. Thus, the fact that a transaction is fictitious according to the national provisions is not sufficient to impair the right to deduct VAT, unless the tax authorities prove abusive behavior and the fraudulent nature of the transaction.