KSeF and paper invoices – changes from 2026

When will KSeF replace paper invoices, and what does this mean for your business?

The year 2026 will bring a revolution in invoicing for Polish businesses. Instead of printing, sending and archiving paper documents, most of us will have to use the National e-Invoicing System (KSeF). This is not a cosmetic change, but a fundamental overhaul of our day-to-day work with sales documentation. In practice, from 1 February 2026, large companies (with a turnover exceeding PLN 200 million in 2024) will be required to switch to e-invoices via the KSeF system, and from 1 April 2026, all other VAT taxpayers – including sole traders, companies, foundations and associations – will follow suit.

From a business owner’s perspective, almost everything is changing: the format, the method of sending invoices, archiving, and access to documents by the accounts department, tax authorities and recipients. However, does this mean the complete end of paper invoices? In practice – not quite. There will still be situations where a paper invoice will be acceptable or even required.

How does KSeF work and how does it differ from traditional invoicing?

KSeF versus paper invoices is a topic that has been causing quite a stir amongst business owners for months. The system operates as a central government platform where you issue and receive so-called structured invoices – files in XML format, compliant with the standard template issued by the Ministry of Finance. In KSeF, every invoice issued is recorded, assigned a unique number, and the document is stored by the system for at least 10 years.

The biggest change? Paper is merely a supplementary medium. It is the data in KSeF that constitutes the original invoice, not a printout or a PDF sent by email. As experts emphasise, “in B2B transactions, the binding document is the XML file downloaded from KSeF. A PDF file or paper printout is merely a presentation of the data from the XML file, intended for review or internal processing”.

In practice, this means that:

• every invoice is automatically delivered to the recipient via KSeF – there is no need to send it by post or email,
• the accounts department has constant, immediate access to all invoices issued and received,
• there is no longer any need to keep track of paper archives, ring binders, duplicates or acknowledgements of receipt,
• the risk of an invoice being lost, destroyed or forged is reduced to virtually zero.

Who else can still use paper invoices after 2026, and when?

Although KSeF and paper invoices effectively mark a move away from traditional documents, the legislator has provided for a number of exceptions. The most important of these are:

1. Sales to consumers (B2C) – if you issue an invoice to a private individual who is not self-employed, you do not have to use KSeF. You may still issue a paper or electronic invoice (e.g. PDF), and the use of KSeF in B2C transactions is voluntary.
2. Foreign business partners without a Polish NIP – if your recipient does not have a Polish NIP, they do not have access to KSeF. In this case, you should send the invoice in the agreed manner: on paper, by email or as a PDF. It is recommended that you include a QR code on the document, which allows the invoice to be verified within the system.
3. Special procedures – sales via the One Stop Shop (OSS), OSS imports (IOSS), single-use tickets for motorways and transport, certain VAT-exempt financial services, or invoices issued by the purchaser (self-invoicing in specific cases) are excluded from KSeF.
4. KSeF system failure or offline mode – in the event of a system failure announced by the Ministry of Finance, you may issue a paper invoice (or an electronic invoice outside the KSeF system), after which you must upload it to the system within a specified timeframe.
5. Micro-entrepreneurs with a gross monthly turnover of less than 10,000 PLN – until the end of 2026, they may issue invoices outside the KSeF system; the obligation will only apply to them from 2027 onwards.

As the Ministry of Finance explains, “after 31 January 2026, sales to consumers may still be documented using a paper or electronic invoice. However, it is possible to issue a structured invoice on a voluntary basis”.

What does the transition to KSeF look like in practice – deadlines and obligations in 2026?

The transition to KSeF is a phased process, depending on the size of the company:

• Large enterprises (turnover exceeding 200 million PLN in 2024) – obligation from 1 February 2026
• Other VAT taxpayers (including sole traders, companies, foundations and associations) – mandatory from 1 April 2026
• Micro-enterprises (gross monthly turnover of up to 10,000 PLN) – mandatory from 1 January 2027

During the transitional period (February–December 2026), taxpayers who have not exceeded the monthly limit of 10,000 zł may continue to issue paper or electronic invoices outside the KSeF system. However, if even a single invoice in a month exceeds this limit, all invoices must be issued via KSeF from that point onwards.

It is worth noting that the obligation to receive invoices via KSeF applies to all domestic businesses from 1 February 2026 – even if you are not yourself required to issue invoices via the system, you must be prepared to receive them.

What are the key differences between a paper invoice and an invoice in KSeF?

The biggest change is not just the medium (paper versus electronic data), but the whole approach to working with documents. A paper invoice required manual archiving, keeping track of deadlines, storing copies and, in the event of an audit, the tedious task of searching for and providing documents. An invoice in KSeF is:

• a standardised XML file format,
• immediate access for authorised persons,
• document integrity (it cannot be ‘tinkered with’ or replaced),
• easy verification of authenticity by the system,
• storage for a minimum of 10 years in a state repository.

From the recipient’s point of view, a paper or PDF invoice is now merely a visual representation of data from the KSeF – it does not constitute an accounting document within the meaning of the law. The original is always the XML file from the system, identified by a KSeF number.

What are the legal consequences of issuing an invoice outside the KSeF after 2026?

In practice, from 2026 onwards, issuing an invoice outside the KSeF (i.e. in paper or electronic form, if it should be structured) may result in serious consequences. The regulations provide for financial penalties of up to 100 per cent of the tax amount or nearly 19 per cent of the transaction value if the KSeF obligation is disregarded. For the recipient, such an invoice may mean that they are unable to deduct VAT or include the expenditure in their tax-deductible costs.

However, as stated in the individual interpretation issued by the Director of the National Tax Information Service on 2 January 2026 (ref. 0111-KDIB3-1.4012.857.2025.1.MSO):

“Receipt of an invoice issued in breach of the obligation to use the KSeF does not deprive the purchaser of the right to deduct VAT, provided that the general conditions set out in Section 86 of the VAT Act are met and the negative conditions set out in Section 88 do not apply.” — Director of the National Tax Information Service, 2026

This is reassuring news for the market – provided that the transaction is genuine and the document contains the required details, the purchaser does not lose the right to deduct VAT, even if the supplier issues an invoice outside the KSeF system (despite being obliged to use it). However, sanctions are imposed on the supplier, not the recipient.

Can a printout from KSeF or a PDF be treated as the original invoice?

No. In the KSeF system, the ‘original’ invoice is an XML file with a unique identification number assigned by the system. A printout or PDF serves solely for information or auxiliary purposes (e.g. providing the document to a consumer, a foreign client or for internal accounting purposes). Such a document may, and often should, bear a QR code that allows the authenticity to be verified and the invoice to be downloaded from the KSeF system.

In practice, for an accountancy firm, an auditor or a tax office, only the document generated by KSeF counts – it is this document that has probative and tax validity.

What are the benefits of switching to e-invoices via KSeF – not just for large companies?

Although for many business owners, KSeF and paper invoices are primarily a bureaucratic necessity, in practice the digitisation of the process brings a number of tangible benefits:

• financial savings – no costs for printing, postage, archiving or document destruction,
• security – data is encrypted and stored by the state for a minimum of 10 years,
• faster document flow – invoices are immediately available to the recipient and the accounts department,
• simplified VAT refunds (processing time reduced from 60 to 40 days),
• reduced risk of errors and forgery,
• easier monitoring and auditing,
• effective integration with accounting and ERP systems – data can be automatically retrieved and processed.

Experience shows that even micro-enterprises quickly come to appreciate the convenience of having automatic access to all invoices in one place and not having to painstakingly collect ‘paperwork’.

How can you prepare your business (and yourself) for the transition to KSeF in 2025/2026?

It is worth starting preparations for the implementation of KSeF as early as 2025, before the system becomes mandatory. Here is a practical action plan:

• Verify your accounting systems – check whether your software is integrated with KSeF 2.0, supports the new formats (FA(3)), the ‘offline24’ mode and the generation of QR codes.
• Staff training – even if you run a sole trader business, familiarise yourself with the rules for issuing and receiving invoices via KSeF, as well as the handling of certificates and authorisations.
• Contingency procedures – draw up instructions in case the system is unavailable (system failure, maintenance work, no internet connection). Learn how to issue invoices offline and submit them to KSeF on time.
• Communication with business partners – inform your customers that, from 2026, a paper invoice is merely a visual representation, whilst the original is stored in the system.
• Archiving – although KSeF stores documents for 10 years, it is worth maintaining your own backups and a digital archive (e.g. in the cloud or on a local server).

Businesses that implement digital procedures now will transition to the new system stress-free and avoid errors during the transition period.

What obligations remain regarding paper invoices following the implementation of KSeF?

Paper invoices will not disappear entirely – in some cases, they will still need to be provided (e.g. to private customers, overseas customers or in emergency situations). It is worth bearing in mind that:

• a printout from KSeF does not have the legal force of an accounting document, but may be required for business reconciliations,
• the archiving of paper documents issued before 2026 remains mandatory in accordance with the existing rules (a minimum of 5 years under tax law, 10 years under financial accounting law),
• paper invoices issued by enforcement authorities, bailiffs and in certain special procedures must be stored and transferred in a specified manner,
• the destruction of paper documents requires compliance with data security procedures (GDPR, certificates, access policy).

Businesses remain responsible for the correct archiving and destruction of their own documents – digitisation does not exempt them from these obligations.

What are the most common questions from businesses regarding KSeF and paper invoices?

In practice, business owners frequently ask about:

• the possibility of issuing paper invoices to consumers after 2026 (yes – this remains possible),
• the transmission of documents to foreign business partners (yes – in an agreed format, e.g. PDF or paper),
• the consequences of suppliers’ errors (e.g. issuing an invoice outside the KSeF system despite the obligation to do so) – here, in accordance with the interpretation of the Director of the National Tax Information Service (KIS) from 2026, the purchaser does not lose the right to deduct VAT,
• archiving invoices from before 2026 (yes – we retain the existing rules),
• issuing invoices offline and in emergency mode (yes – with the obligation to subsequently upload them to KSeF and mark them with QR codes).

Where can you find support and practical assistance regarding KSeF?

If you need professional support with KSeF, we invite you to Firma dla Każdego. Clients have access to accounting, consultancy and invoicing services, regardless of whether they are already on KSeF or are still operating under a hybrid model. The incubator model allows you to test your business safely, make use of a legal entity on loan and avoid high Social Insurance Institution (ZUS) costs at the start. Specialists from the Foundation help guide you through the digitisation process, select the right tools and implement new procedures in accordance with current legislation.

In this era of digitalisation, it is worth drawing on the experience of practitioners who understand the nuances of both KSeF and specific issues relating to paper invoices. This will enable you to enter 2026 without stress or business losses.