Poland Finalizes 2027 KSeF Rules and Tightens Self-Billing Approval Standards

Poland’s national e-invoicing system, KSeF, faces two separate sets of changes this year: a package of structural adjustments scheduled to take effect on January 1, 2027, and a stricter reading of self-billing approval requirements introduced through individual tax rulings issued in 2026.

Structural Changes Taking Effect January 1, 2027

Several provisions tied to the mandatory rollout of KSeF are set to change at the start of 2027:

• Small-taxpayer exemption ends: The current exemption for businesses with monthly gross invoiced sales of up to PLN 10,000 expires on December 31, 2026. Starting January 1, 2027, these taxpayers will also be required to issue invoices through KSeF.
• KSeF invoice numbers in payment messages: From January 1, 2027, an active VAT taxpayer paying another active VAT taxpayer for an invoice issued through KSeF will generally need to include that invoice’s KSeF number in the payment message, where the payment instrument used carries a reference field. This requirement extends to split-payment mechanism (MPP) messages, in which the KSeF invoice number is included in the payment data.
• Collective identifier for bulk payments: Where a single payment settles multiple KSeF invoices, payers may use a “collective identifier” instead of listing each invoice number individually. The identifier is generated within KSeF and can be processed through financial or accounting systems integrated with the KSeF API.
• End of cash-register transition rules: The temporary allowance to issue certain invoices through cash registers outside KSeF expires on December 31, 2026. This also ends the transitional treatment of fiscal receipts bearing the buyer’s NIP (tax ID) as simplified invoices for amounts up to PLN 450.

Previously, on September 16, 2026, the Ministry of Finance announced that penalties specific to KSeF non-compliance would be deferred until the end of 2027. This deferral does not remove the underlying obligation to use KSeF, and implementing it still requires a legislative amendment.

Self-Billing Approval Requirements Interpreted More Strictly

A second development concerns self-billing (self-invoicing) within KSeF. Without any change in legislation, tax authorities have adopted a stricter interpretation of existing approval requirements through individual rulings issued in 2026.

Under this reading, two conditions now need to be met for a self-billed invoice to be considered properly approved:

• Timing: the supplier’s approval must be given before the invoice is submitted to KSeF, not afterward.
• Scope: the approval must cover the structured XML invoice itself, not merely a PDF visualization of it.

KSeF currently has no built-in mechanism for suppliers to approve or reject self-billed invoices, so businesses must manage this approval step outside the platform. Active or tacit acceptance may still satisfy the requirement if the parties have agreed to such terms in advance. Where these conditions are not met, the buyer’s right to deduct input VAT on the self-billed invoice may be put at risk.

Individual rulings issued by the Director of National Tax Information in 2026 illustrate how this is now being applied — for example, rulings 0112-KDIL1-3.4012.874.2025.2.KK (February 27, 2026) and 0112-KDIL1-3.4012.189.2026.1.KK (June 25, 2026).

In each case, the Director held that a self-billed structured invoice must have its content accepted by the seller in XML format before it is submitted to KSeF. Approval obtained only after submission, or covering merely a PDF draft, does not satisfy this requirement. Without proper approval, the invoice does not entitle the buyer to deduct the corresponding input VAT.

Businesses relying on high-volume self-billing arrangements are most exposed to this interpretation, since existing approval processes built around PDF drafts or post-submission sign-off may no longer be considered sufficient. Affected companies are advised to review their self-billing agreements and approval workflows, including any changes needed to ERP and invoicing systems, in light of this interpretation.

There’s more you should know about e-invoicing in Poland – learn more about the new and upcoming regulations.