KSeF – when, what, and who does it apply to? 11 things you need to know about KSeF in the catering industry in 2026.

The introduction of the National e-Invoice System (KSeF) is undoubtedly one of the biggest changes in Polish accounting in recent years. Starting in 2026, new obligations related to issuing, storing, and receiving structured invoices (in XML format) will gradually apply to all entrepreneurs, including restaurant owners.

The National e-Invoice System will go into effect in 2026, but the Ministry of Finance has announced several implementation dates. Therefore, it's worth learning now what the National e-Invoice System is, when it will take effect, and who it applies to. Read on to learn the most important information about the National e-Invoice System!

What is KSeF?

The National e-Invoice System is a central IT platform created by the Ministry of Finance. Its primary purpose is to process VAT invoices in a new, standardized format. Once the National e-Invoice System takes effect, the only legally binding invoice will be the structured invoice stored in the government system.

In practice, this means a complete shift away from the previous model, in which an invoice was associated with a paper printout or a PDF file sent via email. In the new reality, the sales document exists primarily as an XML file, compliant with a state-mandated logical structure. This file, registered in the National Tax Administration (KSeF) and assigned a unique number, will be the sole legal basis for tax settlements.

This is a fundamental change for the restaurant industry, as invoices are often issued in dynamic environments, directly at the guest's service desk. Therefore, it's crucial that the restaurant's sales system is fully prepared to work with KSeF. 

KSeF – since when in gastronomy?

The implementation of KSeF has been staggered, but for the catering industry, 2026 is the key year. From that point on, the system will cover virtually all VAT payers.

According to the current schedule:

• from 1 February 2026, the obligation to use KSeF will apply to the largest enterprises (entrepreneurs whose sales value together with the tax amount exceeded PLN 200 million in 2024),
• from 1 April 2026, KSeF will become mandatory for other VAT payers (including self-employed persons and SMEs) – i.e. for the vast majority of catering establishments,
• from 1 January 2027 – for the smallest companies (sales documented by invoices below PLN 10 per month).

Importantly, from February 2026, entrepreneurs will be obliged to receive cost invoices via KSeF, even if they do not yet issue sales invoices in this system. 

KSeF in gastronomy will be mandatory – there is no escape from it

The first and most important issue is that the National e-Invoice System will not be a voluntary solution. From 2026, using the National e-Invoice System will become a legal obligation for the vast majority of VAT payers, including virtually all restaurants. Restaurants will not be able to decide for themselves whether they want to maintain the current invoicing model – the new system will become the only acceptable option.

For many entrepreneurs, this means the need to completely redefine their document flow, but for restaurateurs using the POSbistro system, it will be just another day of efficient work – thanks to the system being adapted to the KSeF requirements. 

Paper invoices and PDFs no longer have legal significance

One of the most revolutionary changes introduced by the KSeF is the complete overhaul of the definition of an invoice. A document that for years was associated with a paper printout or PDF file no longer has any legal significance in the new system. From the moment the KSeF requirement comes into effect, the only invoice recognized will be one stored in the Ministry of Finance's system.

This has enormous practical implications for the restaurant industry. Restaurant guests can still receive a printout or PDF, but the document will only be a visual representation. The actual invoice, the one relevant to the Tax Office, exists only in the KSeF (National Tax and Customs Office) and has an identification number assigned by the system. Without this number, the document has no legal existence, even if the customer physically receives a printout.

A structured invoice is data, not a document to be read

Another important thing every restaurant owner must understand is the nature of a structured invoice. It's not a document created with humans in mind, but rather with IT systems in mind. An invoice in the KSeF system is an XML file , saved according to a rigid, state-mandated format.

For the restaurant industry, this means the end of freedom in issuing invoices. What matters is not the appearance of the document, but the accuracy of the data: VAT rates, product names, amounts, and buyer details. Any formal error can result in the invoice being rejected by the KSeF, which in practice means the document will not be issued. Therefore, manual invoicing or using unsuitable tools becomes risky and inefficient.

A structured invoice is an electronic document saved according to a strictly defined schema, leaving no room for the arbitrariness known from traditional invoicing programs. Every field, every value, and every tag has a specific meaning and format.

The new model of invoicing in restaurants looks completely different than before. Sales data generated by the POS system is automatically saved in an XML structure and sent directly to the KSeF ( Polish Securities and Exchange Office). The Ministry of Finance's system checks the document for formal accuracy and then assigns it a KSeF number, which clearly confirms that the invoice has been issued.

Only then does the invoice acquire full legal force. Any printouts or PDF files are merely visualizations – helpful to the customer, but insufficient from a regulatory perspective.

The way of issuing invoices in restaurants is changing

In the traditional model, an invoice was considered issued the moment it was saved or printed. In the KSeF, this moment is shifted to the stage of document acceptance by the Ministry of Finance system. An invoice legally exists only when the KSeF assigns it an identification number.

In the restaurant industry, where sales are dynamic, this is crucial. A well-designed POS system must not only generate invoices but also automatically send them to the KSeF and retrieve the invoice number, without involving the staff. This allows waiters to work exactly as before, without having to consider the technical aspects of the entire process.

NIP verification will become standard in the catering industry

KSeF is introducing a new standard for verifying buyer data. Taxpayer Identification Number (NIP) errors are common in the restaurant industry, especially when handling corporate meetings or group orders. The new system makes issuing invoices to inactive or incorrect numbers significantly more difficult.

The POS system, integrated with KSeF, automatically checks the Tax Identification Number (NIP) against the appropriate registers and retrieves the correct customer data. Staff receive a clear message if the number is incorrect. This helps the restaurant avoid corrections, customer misunderstandings, and accounting issues.

The lack of internet will not stop the issuance of an invoice 

One of the biggest technological challenges in the restaurant industry is ensuring sales continuity. An internet outage shouldn't mean a restaurant's operations are halted. Therefore, in the context of KSeF, offline mode is crucial .

Modern POS systems allow invoices to be issued even without a network connection. Documents are saved locally and sent to the KSeF automatically once the internet is restored, maintaining appropriate timestamps. This ensures the premises operate without interruption, while KSeF obligations are handled in the background.

KSeF will also cover cost invoices and restaurant purchases

Many restaurant owners focus solely on sales invoices, but KSeF also covers purchase invoices . Suppliers of food, alcohol, beverages, and other services will issue documents exclusively in the KSeF system.

For restaurants, this means automatic access to cost invoices, without the need for manual data entry or paper document collection. This is a huge simplification in daily work and a significant step towards automating restaurant accounting.

Invoice archiving is transferred to the state system

KSeF also takes over document archiving . Invoices are stored in the system for 10 years, freeing restaurants from the need to maintain paper archives or create backup copies. In practice, this means fewer administrative burdens and greater data security.

One-time KSeF configuration is a prerequisite for the system to function

For a restaurant to use KSeF, a one-time configuration is required, granting the appropriate permissions to the POS system. Without this, the system will not be able to issue or receive invoices on behalf of the business. This process is not complicated, but it does require appropriate technical support.

To begin using KSeF, you must authenticate in the system. Either the entrepreneur or a person or entity designated by the entrepreneur can authenticate. Authentication methods in KSeF include:

• Trusted Profile – a free tool,
• Qualified Signature containing the NIP or PESEL attribute,
• National Certification Center (NCCert),
• Qualified Seal,
• Token-(ultimately the token in KSeF will be replaced by the KSeF Certificate),
• Qualified Signature without NIP or PESEL attribute,
• KSeF Certificate.

KSef and benefits for restaurateurs  

Although KSeF is a top-down change, in the long run it could streamline many processes in the restaurant industry. Automated invoicing, fewer errors, faster VAT settlements, and better document control are real benefits that restaurant owners will appreciate.

KSeF is a new invoicing standard that will become commonplace for the entire restaurant industry in 2026. Restaurants that prepare for this change early and choose the right tools will navigate it smoothly and without disruption to sales.

KSeF at POSbistro

At POSbistro, we've been working intensively on fully integrating our system with the National e-Invoice System for some time now. Our goal is for the POSbistro system to be fully operational when the Ministry of Finance launches the final, production version of the National e-Invoice System.

The preparations include not only the technological layer itself, but also extensive information support for customers on how to use the new functionalities in practice.

POSbistro customers will receive all key functions related to the National e-Invoice System as part of a standard system update, without additional implementations or complicated activities on their part. 

Looking for software for your restaurant? By choosing POSbistro, you gain not only a management tool for your restaurant, but above all, the assurance that your POS system will be ready for the new responsibilities associated with KSeF. Try POSbistro for 14 days free and see what a modern restaurant management tool looks like. 👇