Legal position as at 8 November 2026. All linked sources are in Polish.

KSeF number required in bank transfers from 2027

From 1 January 2027, an active VAT payer that pays a KSeF invoice by bank transfer to another active VAT payer must quote the invoice's KSeF number. If one transfer covers several invoices from the same seller, the payer quotes a collective identifier (IZ) instead.

KSeF (Krajowy System e-Faktur) is Poland's National e-Invoicing System. An active VAT payer (czynny podatnik VAT) is a VAT-registered business that is not exempt.

The obligation comes from Art. 108g of the VAT Act. The payment date decides, not the invoice date: under Art. 17 of the amending act, the provision applies to “płatności dokonanych od dnia 1 stycznia 2027 r.” (payments made from 1 January 2027). A transfer made in January 2027 for a December 2026 invoice that has a KSeF number must therefore include that number. Until the end of 2026, quoting it is voluntary.

Who has to quote the KSeF number?

You quote the number when all three conditions are met:

• You are paying as an active VAT payer. The obligation also applies to a taxpayer settling an invoice on the buyer's behalf, e.g. a parent company paying for its subsidiary.
• The recipient of the money is an active VAT payer. You check their status in the register of VAT payers, known as the White List (biała lista), as at the payment date (Art. 108g ust. 3).
• You are paying by bank transfer or another payment instrument that lets you enter a transfer title (the payment description). The invoice is a structured invoice (one issued in KSeF), or was issued outside the system in offline24 mode or while KSeF was unavailable.

What goes in the transfer title?

The number the seller assigned, e.g. FV/15/01/2027, is not enough. The provision requires the number that identifies the invoice in KSeF.

The collective identifier has 35 characters and covers at least two invoices from one seller. Either the issuer or the recipient of the invoices can generate it, in the KSeF Taxpayer Application (Aplikacja Podatnika KSeF) or in accounting software connected to the KSeF API. To generate it, you need the list of KSeF numbers of the invoices you are paying.

Tomasz runs a workshop and in February 2027 pays a wholesaler for three invoices: PLN 1,230, PLN 615 and PLN 2,460. With three transfers, each one carries the KSeF number of one invoice. With a single transfer of PLN 4,305, Tomasz first generates a collective identifier and enters that in the title.

When is no KSeF number needed?

• The payer is not an active VAT payer. This covers consumers, VAT-exempt businesses and foreign buyers not registered as active VAT payers. The Director of the National Tax Information service (KIS) took that view on a foreign buyer in a tax ruling of 4 December 2025, no. 0113-KDIPT1-2.4012.882.2025.1.AJB.
• The seller is not on the White List as an active VAT payer on the payment date, for example because they use the VAT exemption.
• You pay in cash. The provision covers only transfers and instruments that let you enter a title.
• You pay by card or BLIK (Poland's mobile payment system) at a terminal. The Act does not name them, but we infer from the title condition that the obligation does not cover them.
• The invoice is outside KSeF, e.g. on paper, or a PDF issued in 2026 by a business that did not yet have to use the system. Such an invoice has no KSeF number, even if you pay it in 2027.
• The invoice was not entered into KSeF because of an announced outage (Art. 108g ust. 4).
• You are paying an advance for which there is no invoice yet. Art. 108g refers to payments “za faktury” (for invoices), and a pro forma invoice is not an invoice within the meaning of the VAT Act. A number comes into play only when you pay an advance invoice or a final invoice.
• You settle by offset, because there is then no transfer.

What do the rules leave open?

We found no Ministry of Finance position on three practical points, so what follows is our own reading of the provision.

For a partial payment, Art. 108g makes no exception, and the number identifies the invoice, not an amount. You therefore quote the same KSeF number with each instalment.

A corrective invoice has its own KSeF number. If you are paying an additional amount arising from the correction, you quote the correction's number. The Act does not say what to enter when you pay an invoice reduced by a correction. One transfer then relates to two documents, so a collective identifier seems the safest choice.

Art. 108g also covers an offline invoice that has no number yet because the seller has not sent it to the system. The exclusion applies only to outages announced in an official notice. If the payment deadline allows, pay once the number has been assigned.

What happens if a transfer has no KSeF number?

Art. 108g carries no penalty of its own. The penalties in Art. 106ni, up to 100% of the VAT on the invoice or up to 18.7% of the total amount due, apply to issuing and sending invoices, not to how a transfer is described.

Those penalties were due to apply from 1 January 2027. The Sejm (the lower house of Poland's parliament) passed an act on 6 November 2026 moving them to 1 January 2028, but work on it continues. Neither the government bill nor the amendments tabled in the Sejm change Art. 108g, so the obligation to quote the number starts in 2027 whatever happens to the penalties.

A missing number mainly affects the seller, who cannot match the payment to the invoice automatically.

What should you do before January?

If you pay invoices, check whether your software or bank lets you enter a KSeF number with a transfer and generate a collective identifier. If you sell, load a bank statement into the kto-zaplacil.pl tool: it shows which payments already carry a KSeF number or IZ with a valid checksum.

Sources

• Act of 5 August 2025, Dz.U. (Journal of Laws) 2025 poz. 1203 (Art. 108g, Art. 17)
• Act of 16 June 2023, Dz.U. 2023 poz. 1598 (Art. 106ni, Art. 108a)
• KSeF number and collective identifier, ksef.podatki.gov.pl
• Legislative process, print no. 3245

This article is for information only and is not tax advice.