National e-Invoicing System (KSeF) number in bank transfers in Poland from 2027 – new requirements for companies

From 1 January 2027, a number assigned by Poland’s National e-Invoicing System (KSeF), or a KSeF collective identifier, will be mandatory for certain invoice payments. In the standard case, the requirement will apply to payments between active VAT taxpayers made through an instrument that allows a payment reference. Businesses should ensure the identifier follows the invoice through the entire payment process.

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When will the KSeF number become mandatory in Poland?

The new rules will apply to payments made from 1 January 2027. Until the end of 2026, the requirement under Article 108g of the Polish VAT Act remains deferred.

For a payment covering one invoice, the invoice’s KSeF number will be used. A transfer covering several invoices will require a KSeF collective identifier.

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Who will have to include a KSeF number in a payment?

In the standard case, the requirement applies when:

• the payer is registered as an active VAT taxpayer,
• the recipient is an active VAT taxpayer,
• the payment relates to an invoice covered by Article 108g,
• the payment instrument allows a payment reference to be entered.

The recipient’s VAT status is determined on the payment date using the Polish VAT taxpayer register. The rules may also apply when a taxpayer other than the buyer pays an invoice issued to that buyer.

However, not every transfer connected with a structured invoice automatically falls within Article 108g. The legal nature of the payment, the parties’ status and the payment method also matter.

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How will collective identifiers and split payments work?

A KSeF collective identifier can cover at least two structured invoices issued by the same seller. Businesses should be able both to generate identifiers for outgoing batch payments and decode them when allocating incoming payments.

From 1 January 2027, the KSeF number will also be used in Poland’s split payment mechanism (MPP). A single structured invoice will use its KSeF number, while a batch payment will use a collective identifier.

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Why must KSeF data remain linked to the invoice?

A KSeF number is different from the commercial invoice number assigned by the seller. It is a separate identifier generated after the e-invoice is accepted by KSeF and is not part of the invoice XML file itself.

Businesses therefore need continuity across the entire process:

KSeF → document workflow → ERP / accounting system → approval → accounts payable → payment batch → bank.

For organisations handling hundreds or thousands of invoices, manual searching and re-keying of identifiers increases both workload and the risk of errors.

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What should businesses test before 2027?

KSeF payment readiness should involve accounting, finance and IT. Businesses should verify:

• where the KSeF number is stored,
• whether it remains linked to the invoice after posting,
• whether it flows automatically into payment data,
• how batch payments and collective identifiers are handled,
• whether incoming collective identifiers can be decoded,
• who is responsible for non-standard payment scenarios.

According to the Polish Ministry of Finance, a foreign entity with neither a registered office nor a fixed establishment in Poland is not required to provide a KSeF number or collective identifier for the payment described.

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If you have any further questions or require additional information, please contact your business relationship person or use the enquiry form on the HLB Poland website.

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