Foreign Currency Invoices

Polish law allows invoices to be issued in any currency. This is common in international trade, services for foreign clients, and transactions between Polish companies that have agreed on pricing in EUR, USD, GBP, or another currency. However, specific rules govern how VAT amounts are calculated and what exchange rates must be used.

General Rule — Any Currency Is Allowed

Under Art. 106e(11) of the VAT Act, an invoice may be expressed in any foreign currency. This applies to both domestic and cross-border transactions. There are no restrictions on which currencies can be used.

However, there is one critical requirement: the VAT amount must always be stated in Polish zloty (PLN). Even if the entire invoice is denominated in EUR, the VAT line must show the PLN equivalent. This ensures that both the seller and buyer can correctly report VAT in their JPK_VAT filings, which are always in PLN.

Exchange Rate Rules

The conversion from foreign currency to PLN follows strict rules under Art. 31a of the VAT Act.

Standard Rule (Art. 31a(1))

The exchange rate to use is the last average exchange rate published by the National Bank of Poland (NBP) on the last business day preceding the date when the tax obligation arises.

In most cases, the tax obligation arises on the date of delivery of goods or completion of service (Art. 19a(1)). So in practice:

• If goods were delivered on Wednesday, March 18 — use the NBP average rate published on Tuesday, March 17
• If goods were delivered on Monday, March 16 — use the NBP rate published on Friday, March 13 (the last business day before Monday)

The NBP publishes its average exchange rate table (Tabela A) every business day, typically around 11:45-12:15 CET. The table published on a given day contains rates for that day and is available for use the following day.

ECB Alternative (Art. 31a(2a))

Since January 2021, taxpayers may alternatively use the last exchange rate published by the European Central Bank (ECB) on the last business day preceding the tax obligation date. When using the ECB rate, the EUR/PLN rate is taken directly, while rates for other currencies are calculated cross-rate through EUR.

This option must be applied consistently for at least 12 consecutive months. It cannot be mixed with the NBP method on a transaction-by-transaction basis. The taxpayer must notify the head of their tax office about choosing this method.

Handling Weekends and Public Holidays

When the day preceding the tax obligation date is a weekend or public holiday (and the NBP does not publish a rate), use the last rate published before that non-business day.

For example:

• Tax obligation on Monday, January 5 — use the NBP rate from Friday, January 2
• Tax obligation on Tuesday, January 6 (public holiday in Poland: Trzech Kroli) — but January 5 is a regular Monday, so use the NBP rate from Monday, January 5
• Tax obligation on Monday, May 4, and Friday May 1 was a public holiday — use the NBP rate from Thursday, April 30

Always verify the NBP publication calendar, as Polish public holidays may differ from those in other countries.

Advance Payment Invoices in Foreign Currency

For advance payment invoices (faktury zaliczkowe), the tax obligation arises at the moment of receiving the payment (Art. 19a(8)). The exchange rate to use is therefore the last NBP rate published on the business day preceding the date the advance was received — not the date the invoice is issued.

If the advance is received in a foreign currency, the actual amount received in PLN by the bank may differ from the VAT calculation due to the bank's own exchange rate. This is normal — for VAT purposes, always use the NBP (or ECB) rate as prescribed by Art. 31a, regardless of the actual bank conversion rate.

Intra-Community and Import of Services

For intra-Community acquisition of goods (WNT) and import of services, the tax obligation typically arises on the date of the invoice issued by the foreign supplier. The exchange rate is therefore the last NBP rate published before the date shown on the foreign supplier's invoice.

If the foreign supplier does not issue an invoice by the 15th of the month following the month of delivery, the tax obligation arises on that 15th day, and the exchange rate is taken accordingly.

Final Invoices After Advances

When issuing a final invoice (faktura koncowa) that settles the remaining amount after advance payments, the exchange rate for the remaining portion is determined by the tax obligation date for the final delivery — not the original advance dates. Each portion of the transaction (each advance and the final settlement) may use a different exchange rate.

Exchange Rate Differences and VAT

Exchange rate differences between the invoice date and the payment date do not affect the VAT settlement. VAT is always calculated using the rate applicable on the tax obligation date. Any gain or loss from exchange rate fluctuations is an income tax matter (CIT/PIT), not a VAT matter.

Practical Tips

• Automate NBP rate lookups — the NBP provides a free public API (api.nbp.pl) that returns exchange rate tables in JSON and XML formats. Integrating this into your invoicing software eliminates manual errors
• Cache rates daily — since rates are published once per business day, cache them to avoid repeated API calls
• Document the rate used — while not legally required on the invoice itself, recording the NBP table number and date used for each foreign currency invoice is invaluable during audits
• Watch for rate publication timing — if you issue invoices early in the morning, the current day's NBP rate may not yet be published. This is fine because you always use the previous business day's rate for the tax obligation date
• PLN-denominated invoices for foreign buyers — there is no requirement to issue in the buyer's currency. You may issue an invoice in PLN even for a foreign client, though commercial practice often favors issuing in their currency