An invoice is a fundamental and obligatory document providing evidence of transactions made, which are a subject to value added tax (VAT). In order to contribute to transparency in business transactions taxpayers should ensure the authenticity of the origin of invoices, integrity of their content as well as their legibility. The authenticity of the origin of an invoice is understood as the certainty of the identity of the supplier of goods or services or the issuer of the invoice. Moreover, the principle of integrity of the content of the invoice implies the immutability of the data included on a given version of the invoice. Finally, legibility means that the content of invoices shall be transparent and clear. Each invoice should be issued in at least two copies if issued on paper – one for the purchaser and one for the taxpayer, but nowadays invoices are most often issued in electronic form. Proper invoicing is essential to ensure legitimate VAT reporting and correctness of data contained in SAF-T files.

What elements are obligatory on the invoice?

Invoices issued by taxpayers shall include at least the following details, mentioned in Article 106e of the Polish VAT Act:

• a date of issuance,
• names of the taxpayer and the purchaser of goods or services and their addresses,
• a number identifying the invoice,
• a subject (type) of the goods or services,
• net unit price,
• net sales value,
• gross amount,
• an amount of VAT in PLN,
• a VAT rate,
• VAT numbers of the taxpayer and the purchaser of goods,
• measure and quantity (number) of goods delivered or range of services performed,
• a date of supply of goods or services or its completion or a date of a payment receipt received (in case of advance payments),
• amounts of any discounts or price reductions, including in the form of a discount for early payment, to the extent that they have not been included in the net unit price.

Moreover, in case invoices are raised in foreign currencies, exchange rates used for recalculations of VAT amounts into PLN can be additionally included.

Rules of converting to PLN

Speaking of the amount of VAT in PLN on the invoice, it is crucial that the taxpayer convert the foreign currency at the right exchange rate. The exchange rate should be taken from the last working day proceeding the day of the tax point occurrence. For this purpose taxpayers can use exchange rates announced by National Bank of Poland (NBP) or European Central Bank.

However, if an invoice in foreign currency is issued before related tax point arises, the conversion to PLN shall be made according to exchange rate announced by the NBP (or ECB) on the last working day preceding the day of invoice issuance.

Storage and invoices issuing deadlines

Based on Polish VAT regulations, an invoice shall be in general issued no later than the 15th day of the month following the month, in which a delivery of goods was made or services performed. However, there are a few specific exceptions, when the taxpayer has 30, 60 or even 90 days to issue an invoice. Moreover, an invoice should not be issued earlier than 60 days before a delivery of goods, supply of service or receipt of a payment or its part.

Taxpayers are obligated to store issued or received invoices. Invoices shall be stored based on accounting periods and in an organized way, which allows to find them promptly. This solution allows tax authorities an easy access to invoices. In general, invoices must be kept for at least 5 years, starting from the end of the calendar year in which the tax is due.

Structured invoices

Additionally, the National e-Invoicing System (KSeF), also called ‘structured invoices’, according to the current position of the Ministry of Finance, the KSeF will probably be introduced in stages: from 1st February 2026 for taxpayers with annual turnover above 200m PLN, and from 1st April 2026 for all another taxpayers. In general, it will be mandatory for all active VAT taxpayers, however, the obligation for e-invoicing will not apply to taxpayers who do not have a registered office or a fixed establishment for VAT purposes in the territory of Poland. In such case, using KSeF will be optional, therefore most foreign companies can continue to issue invoices without change. When a contractor issues an invoice in KSeF, he will be obliged to provide such invoice in another way mutually agreed beforehand.