Implementation of the National e-Invoicing System – what should you prepare for?

From 2026, invoicing in Poland will undergo a significant transformation. Implementation of the National e-Invoicing System (KSeF) will be mandatory for both large entities and micro-entrepreneurs and sole proprietors. Companies that adapt their procedures, tools, and teams in advance will have the opportunity to implement the changes efficiently and avoid disruption and costly mistakes.

National e-Invoicing System (KSeF) – What Is It And How Will It Affect Everyday Business Operations?

The National e-Invoicing System (KSeF) is a government platform for issuing, receiving and archiving invoices in a uniform electronic format.

Key practical changes:

• the XML format invoice will become the primary document,
• each invoice is sent to the system at the time of issuance,
• the buyer downloads the invoice directly from the KSeF system,
• the tax office gains a real-time insight into the invoice workflow,
• paper and PDF formats will cease to be the primary form of settlement.

For micro-entrepreneurs, this means the need for full digitisation of the sales and purchase process.

KSeF Implementation Timeline – Who And When Will Be Affected by the National System of E-Invoices

Implementation of the National e-Invoicing System in Poland. How Can Micro-Entrepreneurs And Sole Proprietorships Use the KSeF?

Entrepreneurs can use either free or paid solutions:

• Free tools provided by the Ministry of Finance.  The “e-mikrofirma” application and the KSeF interface allow for invoicing. This is sufficient for a small-scale business.
• IT integrations. With a larger number of invoices, automation will be necessary (e.g. sales systems integrated with the KSeF).
• Commercial solutions. Some companies (e.g. Symfonia) offer versions that allow you to send a limited number of documents per year.

It is crucial to adapt the solution to the scale of the business. A sole proprietorship issuing several invoices per month does not need expensive ERP systems.

How to Start The Implementation of the National e-Invoicing System And Get Access to the KSeF?

Preparatory steps:

• Automatic account – every entrepreneur with a tax ID already has a KSeF account.
• Login – available via Trusted Profile, e-ID card, or qualified electronic signature.
• Company access – requires filing the ZAW-FA form and appointing an authorised representative.
• Testing – use of the demo version and test environments.

Tokens and certificates – key security elements

• Tokens – electronic keys that enable the integration of the sales system with KSeF without logging in each time.
• Certificates –from February 2026, they will be used alongside tokens, providing higher security.
• Practice – with tokens, an entrepreneur continues issuing invoices in their system, and the document is automatically sent to KSeF.

System testing – why can this stage not be skipped?

Experts point out that skipping testing is the most common mistake in implementation.

Benefits of testing:

• familiarisation with the taxpayer’s application interface,
• possibility to test the full invoicing process,
• verification of data accuracy,
• elimination of errors before the mandatory launch.

Implementation of the National e-Invoicing System And the Role Of an Accounting Office

Many entrepreneurs assume that an accountant will handle the implementation. This is a misunderstanding because:

• The accounting office does not issue invoices or manage the sales process,
• The responsibility for implementation lies with the entrepreneur,
• The office can perform an advisory function. For example, recommend IT solutions, provide training in record-keeping, and assist with tax interpretation.

Implementation of the National e-Invoicing System (KSeF) – Most Common Problems And Risks

• mistaken assumption that implementation concerns only accounting offices,
• lack of preparation for receiving invoices as early as February 2026,
• problems with attachments (inability to add delivery protocols or cost estimates in PDF),
• risk of errors when working offline,
• postponing action until the last moment.

Implementation of the National e-Invoicing System – Summary

The implementation of the National e-Invoicing System (KSeF) is an obligation that cannot be avoided. For some entrepreneurs, it will be a revolution, for others, it will be a natural step in digitisation. The key, however, is not to delay the start. Process analysis, choice of tools, training, and testing are essential to transition to KSeF without sanctions or business disruption.

Do you need support in the safe implementation of the National e-Invoicing System (KSeF)? Our law firm will guide you through the entire process – from analysis to preparation of procedures. Contact us.

FAQ – Questions And Answers About Implementation Of The National e-Invoicing System