The tax clarifications of October 16, published by the Ministry of Finance on the recognition of NIP fiscal receipts as simplified invoices, certainly cannot be considered as simplifying and organizing the confusion existing in this area, especially in the retail industry. In the opinion of the Ministry of Finance, each fiscal receipt with NIP up to PLN 450 (EUR 100) is considered a simplified invoice and therefore it is not possible to issue an ordinary invoice for such a receipt. This may result in a penalty in the form of double payment of the VAT amount pursuant to Art. 108 of the VAT Act.
Source MDDP (in Polish)