Penalties for failure to integrate with KSeF – what are the consequences for your company?

The introduction of the National e-Invoicing System (KSeF) as of February 1, 2026 marks a revolution in the way invoices are issued and received in Poland. The obligation to use KSeF applies to large companies as early as February 2026, followed by smaller companies from April 2026. One of the key aspects of this change is that only an invoice issued and received through the KSeF system will be considered a valid tax document. What does this mean for your company and what penalties will you face for not integrating with KSeF?

Why is integration with KSeF mandatory?

KSeF is the Ministry of Finance's central platform for issuing, sending and archiving invoices in a structured electronic format. This allows tax authorities to control and analyze transactions faster, reducing the risk of tax fraud.

Companies that do not integrate their invoicing systems with KSeF will not be able to properly issue and receive compliant invoices. What's more, invoices sent through traditional channels, such as email or paper, without an acknowledgement of receipt by KSeF, will not be considered tax documents. This means that the counterparty will not be obliged to pay them - and your company may have trouble collecting the receivables.

What are the risks of not integrating with KSeF?

1. Risk of rejection of invoices by clients and customers
   Without KSeF uploading the invoice, the document will not have the status of a valid VAT invoice. Recipients may refuse to accept and settle such a document, which in practice means liquidity problems.
2. Possibility of financial penalties
   Non-compliance with the KSeF obligation can result in tax audits and penalties for improper accounting records. Sanctions can range from fines to other financial consequences.
3. Problems with VAT deduction and tax settlements
   Invoices outside of the KSeF system may be challenged by tax authorities, which can hinder VAT deductions and lead to billing adjustments.
4. Loss of business confidence
   Contractors, especially large companies and public institutions, are increasingly demanding compliance with KSeF as a condition for cooperation. Failure to integrate can result in the loss of key customers and partners.

Does an emailed invoice have to be paid?

According to current regulations, an invoice must be issued and received by KSeF to be a tax document. An invoice sent only by email, without the intermediation of the KSeF system, does not meet this requirement. In practice, this means that:

• Email invoices without confirmation of receipt by KSeF are not invoices in the sense of tax law.
• The recipient of an invoice has no legal obligation to pay it if it was issued outside KSeF (unless the parties agree otherwise).
• Such an invoice does not allow for proper accounting for VAT or showing it in the VAT register.

How to prepare your company for integration with KSeF?

• Verify your financial and accounting systems for KSeF readiness - check whether your ERP or invoicing software allows integration.
• Use a professional technology partner to ensure fast and secure KSeF implementation and support during the process.
• Train your invoicing and billing staff to minimize the risk of errors and delays.
• Implement a contingency plan for technical problems with KSeF, such as a local document archive and monitoring of invoice statuses.

Failure to integrate with KSeF carries serious financial and operational consequences for any company operating in the Polish market. Only invoices issued and received by the KSeF system will be considered valid tax documents, while invoices sent traditionally, e.g. by email, will not have such status and may not be paid by contractors. To avoid penalties and liquidity problems, it is advisable to implement the appropriate integration solutions as soon as possible and ensure full compliance with the new requirements.

Download the free e-book: "Infinite KSeF - a guide to e-invoicing in Poland and around the world".

Do you want to carry out a KSeF implementation without errors, delays and the risk of process paralysis?
In our e-book you will find:

• A practical discussion of KSeF - responsibilities, deadlines and impact on your organization
• E-invoicing in Europe - a map of responsibilities in 15 countries
• 5 strategic trends that every CFO should know
• 7 pitfalls in implementing KSeF and how to avoid them
• How AI and automation are changing the face of finance
• A ready-made action plan - step by step

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