Mandatory E-Invoicing in Poland: What Businesses Need to Know

In 2026, Poland introduced mandatory electronic invoicing via the Krajowy System e-Faktur (KSeF). KSeF is the Polish government’s central platform for issuing, receiving, and storing structured electronic invoices.

The implementation is taking place in phases. As of February 1, 2026, the requirement to send invoices via KSeF applies to companies whose revenue, including VAT, exceeded 200 million Polish złoty in 2024. As of April 1, 2026, the requirement applies to virtually all other businesses. Only the smallest businesses, with a maximum of 10,000 złoty in monthly invoiced revenue, have been granted a deferral until January 1, 2027.

A different deadline applies to receiving invoices. Since February 1, 2026, businesses covered by the system must be able to receive invoices via KSeF, regardless of when they themselves become required to issue invoices via KSeF.

What changes will the Polish requirement bring?

KSeF changes not only the format of the invoice but also the way invoices are exchanged between businesses. For regular transactions, a structured invoice is sent from the financial or invoicing system to KSeF. When the invoice is accepted by the system, it receives a unique KSeF number and becomes available to the customer via the platform.

A standard PDF sent directly via email to a Polish customer therefore does not comply with the mandatory KSeF procedure if the transaction falls under the mandate.

In principle, the requirement applies to Polish taxpayers with a place of business in Poland and to foreign companies with a Polish permanent establishment, provided that such permanent establishment is involved in the transaction in question. A foreign company that only has a Polish VAT number but no place of business or relevant permanent establishment in Poland is, in principle, not subject to the mandatory KSeF outbound invoicing requirement.

Invoices to consumers are exempt from the mandatory KSeF system. However, businesses may voluntarily issue B2C invoices via KSeF.

What is KSeF?

Krajowy System e-Faktur, or KSeF for short, is Poland’s national system for structured electronic invoices. Unlike in Germany, for example, where businesses can use various channels to exchange e-invoices directly with one another, in Poland the central government platform plays a direct role in the invoice flow.

The sender creates the invoice in their ERP, accounting, or invoicing system and sends the structured data to KSeF. Among other things, the system verifies whether the document technically complies with the prescribed structure. Upon acceptance, a unique KSeF number is assigned, and the recipient can receive the invoice via KSeF.

KSeF thus serves simultaneously as an infrastructure for invoice exchange and as a source of information for the Polish tax authority. Through the system, the tax authority has access to the data from the structured invoices.

The Polish FA(3) invoice format

A Polish KSeF invoice is not exchanged as a PDF, but as a structured XML file. Since February 1, 2026, the FA(3) structure published by the Polish Ministry of Finance must be used for this purpose.

The structure specifies which data may or must be included in the invoice and in which fields it is recorded. This includes supplier and customer information, invoice date, goods or services, VAT rates, amounts, and payment details.

The ERP or invoicing system converts the invoice data into an XML file compliant with FA(3). KSeF then verifies whether the file technically conforms to the prescribed schema. A file that does not comply with the structure will not be accepted by the system.

A visual PDF version can still be used to make an invoice readable by humans, but the structured XML file constitutes the actual electronic invoice within KSeF.

How are Polish e-invoices exchanged?

For regular KSeF transactions, the official invoice exchange takes place via the central system. Organizations can use the applications provided by the Polish Ministry of Finance or connect their own financial software to KSeF through a technical integration.

For larger organizations, such integration is typically part of the existing ERP and invoicing process. Invoices are generated from the source system, converted to the required FA(3) structure, and sent to KSeF. On the receiving end, organizations must then retrieve their KSeF invoices and process them in their financial accounting systems.

KSeF also has procedures for situations in which an invoice cannot be processed directly online. Through offline24, under certain conditions, an invoice can be created outside the direct online connection, after which it must be sent to KSeF no later than the next business day. Additional rules apply to such invoices, including the use of QR codes.

International Transactions and Foreign Companies

KSeF is primarily a Polish tax obligation, but its scope is not limited to Polish customers.

For example, when a taxpayer based in Poland supplies goods to a company in another EU member state, exports goods, or provides services to a foreign company, the Polish supplier must , in many cases , issue the relevant invoice via KSeF.

The foreign customer does not need to be connected to KSeF themselves for this purpose. The Polish supplier then also provides the invoice in a manner agreed upon with the customer, for example, electronically outside of KSeF. Additional requirements, such as a KSeF QR code, may apply in such cases.

Conversely, invoices from a foreign supplier to a Polish company do not need to be reported to KSeF as foreign purchase invoices.

For international companies, therefore, the status of the Polish entity or permanent establishment is the primary determining factor. A Polish VAT registration number alone does not automatically mean that the foreign company is required to invoice via KSeF.

The Role of Peppol and Invoicing to the Government

Poland has long used electronic invoicing for government contracts via the Platforma Elektronicznego Fakturowania (PEF). PEF uses Peppol for the electronic exchange of documents with public organizations.

Since the introduction of KSeF 2.0, KSeF and PEF have been interconnected. An e-invoice for a government contract sent via PEF and Peppol that complies with the European standard EN 16931 can be treated as a structured invoice within the Polish VAT system after being transmitted to KSeF.

Peppol thus plays a different role in Poland than it does, for example, in Belgium. For regular Polish B2B invoicing, Peppol is not the central network: KSeF is the mandatory infrastructure. Peppol remains particularly relevant for the public sector and international document exchange.

What does ViDA have to do with Poland?

The Polish KSeF requirement is a national e-invoicing regulation and is separate from the European Digital Reporting Requirements that ViDA will introduce as of July 1, 2030, for relevant cross-border B2B transactions.

Poland, therefore, is not waiting until 2030. Through KSeF, the Polish tax authority already has direct access to structured invoice data for a large portion of Polish companies’ transactions.

Starting in 2030, ViDA will also introduce a harmonized European framework for e-invoicing and digital reporting for cross-border transactions. For organizations with operations in Poland, this means they must take into account both the current Polish KSeF requirements and the European rules that will later apply to cross-border transactions.

The Polish Roadmap for E-Invoicing

• February 1, 2026: KSeF 2.0 becomes mandatory for companies with more than 200 million złoty in revenue (including VAT) in 2024. As of this date, receiving invoices via KSeF becomes mandatory for companies covered by the system.
• April 1, 2026: The requirement to issue invoices via KSeF will be extended to virtually all other businesses.
• Through December 31, 2026: Companies with monthly invoiced revenue of up to 10,000 złoty may, under certain conditions, continue to issue invoices outside the KSeF system. Furthermore, in 2026, no specific KSeF penalties will yet be imposed for errors in using the system.
• January 1, 2027: Even the smallest businesses will be subject to the KSeF outbound invoicing requirement, and the standard penalty regime may be applied.
• July 1, 2030: ViDA introduces European e-invoicing and digital reporting for relevant cross-border B2B transactions.

What does this mean for organizations?

For organizations with a Polish entity, KSeF is no longer a future development. The requirement will take effect in 2026 and affects both the outgoing and incoming invoicing processes.

This involves more than just being able to generate an FA(3) file. The financial system must be able to convert, validate, and send invoices via KSeF; process the KSeF status and the assigned number; and automatically retrieve incoming invoices and forward them to the financial accounting system. International invoice flows, permanent establishments, self-billing, exceptions, and offline procedures require separate attention.

For international organizations, it is therefore becoming increasingly clear that e-invoicing cannot be addressed with a single European format or a single transmission channel. Belgium primarily uses Peppol, France uses accredited platforms, Germany uses decentralized exchange, and Poland uses the central KSeF platform. An international e-invoicing architecture must be able to accommodate these different national models.