- Article 108(1) of the VAT Act: anyone who issues an invoice showing VAT must pay that VAT — even without registration.
- Tax arrears: VAT on all sales that should have been taxed from the start, plus late-payment interest.
- Fiscal penal liability under the Fiscal Penal Code for failing to register and failing to pay the tax.
The longer the error lasts, the bigger the bill. Fixing it takes an accountant: filing VAT-R, correcting documents and, where possible, filing a voluntary disclosure (czynny żal).