Poland's KSeF system requires new invoice identifiers for split payments from January 2027

Poland’s National e-Invoicing System (KSeF) introduces a technical change to how invoices are identified in split payment transfers. From 1 January 2027, businesses must reference the KSeF-assigned invoice number or collective identifier in payment messages, not the seller’s invoice number. The split payment rules themselves do not change, but companies must update their payment procedures, accounting systems and approval workflows to handle the new identifiers.

What changes on 1 January 2027

Poland’s split payment mechanism remains unchanged in its core rules. The decisive factors stay the same: the Polish VAT Act provisions, invoice value, party status and goods or services type. What changes is the technical link between payment and structured invoice.

From 1 January 2027, businesses must correctly identify invoices in split payment transfer messages using either the KSeF invoice number (for single invoices) or the collective identifier (for multiple invoices). This applies to all payments relating to structured invoices issued through KSeF.

How split payment works

The split payment mechanism divides an invoice payment into two parts:

• Net amount goes to the supplier’s settlement account
• VAT amount goes to the supplier’s dedicated VAT account

The buyer initiates this using a dedicated split payment transfer message from their bank. The message includes the VAT amount, gross amount, seller’s Tax Identification Number (NIP) and data linking the payment to the invoice.

In the existing model, the invoice number assigned by the seller was the key reference. With KSeF, the system-generated KSeF invoice number becomes essential. This number clearly identifies the document in Poland’s e-invoicing system.

When split payment is mandatory

Mandatory split payment applies when all three conditions are met:

• The invoice documents a transaction between taxpayers (B2B)
• The total amount due exceeds PLN 15,000 or its equivalent
• The invoice covers goods or services listed in Annex 15 to the Polish VAT Act

The buyer should independently assess whether goods or services are subject to mandatory split payment. The absence of split payment wording on an invoice does not always release the buyer from the obligation.

Invoice number versus KSeF number

Businesses may now deal with several identifiers for the same invoice:

• The invoice number assigned by the seller (part of the accounting document)
• The KSeF number assigned by the system after the structured invoice is accepted
• The collective KSeF identifier (if payment covers multiple structured invoices)

For payments relating to structured invoices, the KSeF number becomes the key identification reference. Data must remain consistent across the invoice, accounting system, online banking and VAT records. Errors may prevent automatic payment-to-invoice matching and create reconciliation problems.

Single invoice payments

When paying one structured invoice subject to split payment, the dedicated split payment transfer message should include:

• The VAT amount shown on the invoice (or part of it)
• The gross sales value (or part of it)
• The KSeF number identifying the invoice
• The seller’s Tax Identification Number (NIP)

If the payment covers only part of the amount due, the amounts in the transfer message must correspond to that partial payment. Split payment transfers apply only to payments in Polish zloty. For foreign currency invoices, businesses must follow Polish VAT conversion rules.

Collective payments for multiple invoices

The Polish VAT Act allows one split payment transfer to cover multiple invoices from the same supplier, provided the invoices were issued within a period of not less than one day and not more than one month.

For structured invoices issued through KSeF, a collective payment may cover selected invoices from one supplier during that period. Businesses do not have to include all invoices from a given supplier in one transfer; they may choose which invoices to pay.

Instead of entering individual invoice numbers or a period in the transfer message, the business indicates the collective identifier assigned by KSeF. This identifier aggregates the KSeF numbers of the invoices included in the payment.

Difference from non-KSeF invoices

For invoices outside KSeF, the split payment transfer message must cover all invoices issued by one supplier within the given period. The period is entered in the field intended for the invoice number.

For structured invoices in KSeF, the transfer message may cover selected invoices. The collective KSeF identifier is indicated instead of a period. This difference affects payment planning and requires companies to adapt internal procedures.

What buyers should verify before payment

Before making payment, the buyer should check:

• Whether the invoice value exceeds PLN 15,000 or its equivalent
• Whether the invoice covers goods or services listed in Annex 15 to the Polish VAT Act
• Whether the payment concerns the whole invoice, part of it, or several invoices
• Whether the invoice is a structured invoice issued in KSeF
• Whether the KSeF number or collective identifier should be used
• Whether the VAT amount in the transfer message corresponds to the payment covered by split payment

In larger organisations, these checks should be built into the invoice workflow. Where purchasing, approval, accounting and payment are handled by different people or departments, clear procedures are essential.

Preparation steps for businesses

Preparation for KSeF should not be limited to issuing and receiving structured invoices. Businesses should also:

• Review payment procedures
• Update accounting systems
• Revise internal invoice approval workflows
• Ensure the KSeF number, collective identifier, VAT amounts and supplier data are correctly transferred between systems
• Train staff responsible for settlements

This is especially important for companies that regularly receive invoices subject to mandatory split payment, settle multiple invoices from the same supplier, or use finance and accounting systems integrated with online banking.

The split payment mechanism has been extended until 2028, so businesses should treat it as a permanent part of tax and payment processes rather than a temporary solution.

References

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1. Ministerstwo Finansow, KSeF: numer KSeF i zbiorczy identyfikator
2. getsix (PL, EN + PL editions)