The National e-Invoice System (Krajowy System e-Faktur, KSeF) represents the most significant change in Polish invoicing in years. After multiple postponements, the matter is now settled – on August 27, 2025, President Karol Nawrocki signed the law implementing KSeF. The Ministry of Finance confirmed on December 11, 2025, that it is not considering any further postponement of the mandatory KSeF launch.

Just over a month remains until the obligation takes effect – this is the final opportunity to prepare.

What is KSeF?

The National e-Invoice System is an IT platform operated by the Ministry of Finance for issuing, receiving, and storing structured invoices in a unified XML format. In practice, instead of sending an invoice by email or post, entrepreneurs issue it through KSeF, from where the buyer can download it. Simultaneously, the invoice is automatically transmitted to the tax administration.

A structured invoice differs from traditional paper invoices or PDFs in that it has a predefined structure, making data consistent and automatically processable by accounting systems. This marks the end of paper invoices, PDFs, Word, or Excel documents – they will be replaced by a unified, structured XML file with a KSeF number.

Implementation Timeline – 2026 Schedule

The system is being implemented in phases:

• February 1, 2026 – mandatory for large entities (2024 turnover exceeding PLN 200 million gross)
• April 1, 2026 – mandatory for all other entrepreneurs (micro, small, and medium enterprises)
• January 1, 2027 – mandatory for the smallest taxpayers (monthly sales up to PLN 10,000 gross)

NOTE: The key factor in determining the deadline is gross sales value achieved in 2024, not 2025. Taxpayers can already determine exactly when they will need to comply with the new obligation.

The obligation to receive e-invoices through KSeF will apply to all entrepreneurs from February 2026. Even if a given entrepreneur does not yet have to issue invoices through the system, they will have to receive them there – this includes invoices for electricity, telecommunications, or fuel from large suppliers.

Implementing Regulations – December 2025

In December 2025, the Minister of Finance and Economy signed four implementing regulations concerning KSeF operations:

• Regulation on KSeF usage (December 12, 2025) – defines rules for using the system, including the ZAW-FA notification form, user authentication methods, and procedures for granting and revoking permissions
• Regulation on KSeF exemptions (December 7, 2025) – specifies cases where there is no obligation to issue structured invoices
• Regulation amending invoice issuance rules (December 7, 2025) – adapts simplified invoice issuance rules
• Amendment to JPK_VAT regulation (December 12, 2025) – effective December 18, 2025, applies to reporting periods from February 1, 2026

New JPK_VAT Designations from February 2026

New designations will appear in the JPK_VAT sales and purchase records under the KSeF node:

• OFF – invoice issued in offline mode that does not yet have a KSeF number as of the filing date
• BFK – electronic invoice or paper invoice (issued outside KSeF)
• DI – document other than an invoice issued through KSeF

The requirement to provide the KSeF number in JPK_VAT will apply to invoices issued through KSeF regardless of the mode of issuance and transmission (offline 24, system failure, system unavailability).

Who Will Be Affected?

All VAT taxpayers issuing invoices in B2B transactions will be required to use KSeF, including:

• Active and VAT-exempt taxpayers (if they issue invoices)
• Foreign entities registered as VAT taxpayers in Poland
• Businesses of all sizes – from sole proprietorships to corporations

Exemptions: Consumer sales (B2C) – invoicing through KSeF remains voluntary and simplified. Certain VAT-exempt services may also be invoiced outside the system.

Key Dates – What Has Already Happened

• From November 1, 2025 – entrepreneurs can apply for invoice issuer certificates (KSeF certificates), required for system authentication and for issuing e-invoices in offline mode
• From November 2025 – test version of KSeF 2.0 Taxpayer Application available (invoices issued in the test environment have no legal effect)
• From January 1, 2026 – the e-Tax Office launches a notification module enabling declaration of intent to issue invoices with attachments
• December 18, 2025 – regulation adapting JPK_VAT to KSeF came into force

Benefits of KSeF

• Faster VAT refund – 40 days instead of the standard 60 days, improving cash flow for entrepreneurs
• No archiving obligation – the system assumes responsibility for storing e-invoices
• Elimination of duplicates – invoices cannot be lost in KSeF, no need to issue duplicates
• Process automation – ability to automatically import data from purchase documents into financial and accounting systems
• Reduced error risk – structured format limits mistakes in invoice processing

Penalties for Non-Compliance

For non-compliance (e.g., not issuing an invoice through KSeF, issuing it bypassing the system, or failing to submit it on time after a system failure), the head of the tax office may impose a financial penalty:

• Up to 100% of the tax amount shown on the invoice
• Up to 18.7% of total amount due – for invoices without tax shown

However, the introduction of penalties has been deferred – during the initial period of system operation, the tax administration will conduct educational activities to support taxpayers.

How to Prepare? Final Month Checklist

• Complete identification in the KSeF taxpayer application – create an account and verify your identity
• Obtain an invoice issuer certificate – required for issuing invoices in offline mode and in case of system failure
• Integrate your invoicing/accounting software with KSeF – contact your software provider and test the integration
• Establish KSeF access permissions – determine who in the company will be able to issue and receive invoices
• Train employees – familiarize your team with the new invoicing process
• Develop emergency procedures – prepare for issuing invoices in offline mode in case of system unavailability
• Test the system – use the KSeF 2.0 test environment to verify processes before the obligation takes effect

Summary

KSeF represents a revolution in Polish invoicing that will affect virtually all entrepreneurs. Although it is not a new tax, its impact on daily business operations will be comparable to major tax reforms. The deadline is final – the Ministry of Finance has clearly confirmed that no further postponements are planned.

For accounting firms, it will be crucial to test integration with client systems early, establish procedures for system failures, and train employees. Preparations should begin immediately – only one month remains until the first phase of the obligation takes effect.