According to Polish VAT Act, the invoice shall be issued in two copies, from which one is forwarded to the customer.
The invoice shall be raised not earlier before 30 days preceding the date of delivery of goods or services and not later than within 15 days following the month for which the goods or services have been delivered. There are also other terms for issuance of the invoice, however they will not apply for this case, hence they will not be presented in this analysis.
In case of receiving the payment or partly payment before the date of delivery of goods or services, the invoice shall be issued not later than within 15 days following the month in which the payment or partly payment has been received.
According to Polish invoicing rules, the taxpayer is allowed to issue an invoice or simplified invoice. The simplified invoices may be issued only if maximum value for of a transaction does not exceed the amount of EUR 100 or PLN 450. The only exceptions where the simplified invoiced are not allowed is distance sales and intracommunity deliveries.
Source Polishtax.com
