Section 26 of the Value Added Tax Act requires the payer to issue an invoice (lit. daňový doklad - tax document) within 15 days of the taxable activity (point 1a ode dne uskutečnění zdanitelného plnění) , in Polish law, the date of the action referred to as the date of sale. The same paragraph in the next point requires the invoice to be issued no later than on the 15th day from accepting the payment.

Paragraphs 21, preceding §26, define in detail the moment of granting tax for taxable services (activities), while the first sentence is of fundamental nature for the given problem."The tax on exit is required to be paid by the payer on the day when the taxable activity is rendered or on the day when the payment is accepted, taking into account the date that is earlier, unless the law provides otherwise."

In the case of delivery of goods, the day of sale is considered to be:
a) the day of delivery when selling under a contract of purchase between contractors,
b) the day of receipt in other cases,
c) day of bidding in auctions,
d) day of acquiring the right to use the rented goods.

The above rules are subject to an exception for intra-Community supplies of goods, where the date of sale is the date of invoice, provided that the invoice is issued before the 15th day of the month following the shipment or commencement of movement of the goods. Otherwise, the date of sale is the 15th of the month following that. It follows from the above that the latest date of sale is the 15th day of the month following the commencement of delivery of the goods.

In the case of intra-Community supplies of services, the EU regulations the legislator once again returns to the fundamental principle of the date of sale of the service or acceptance of payment for it and imposes an obligation to issue an invoice within 15 days.

For domestic deliveries, accepted invoices will have the right to deduct at the earliest on the day the invoice is received.