Legal status: December 2025
After several years of announcements, tests, and postponements, the National e-Invoice System (KSeF) is entering its mandatory phase. For many entrepreneurs, this isn't just "another VAT change," but a real revolution in the way invoices are issued, transmitted, and archived.
From 2026, the invoice will cease to be a document "sent to the customer" and will instead become a document functioning within the state system. This will force changes not only in accounting but also in sales, IT, document flow, and workflow.
What is KSeF and what does it change in practice?
KSeF, or the National System of e-Invoices, is a central IT platform through which entrepreneurs will issue structured invoices.
In practice, this means that:
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the invoice is deemed to have been issued when it is accepted by KSeF,
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we no longer send invoices by email as PDF (unless in certain exceptions),
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the buyer receives the invoice via the system or in a manner related to it,
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the rules for corrections, duplicates, dates of issue and storage of documents are changing,
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System permissions, powers of attorney and access control become crucial.
KSeF is not just an accounting tool. It's a system that influences the entire sales process.
When will KSeF become mandatory?
According to current regulations, the obligation to use KSeF will be introduced in stages:
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from 1 February 2026 – for entrepreneurs whose sales (including VAT) exceeded PLN 200 million in 2024,
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from 1 April 2026 – for other taxpayers issuing invoices (both active and exempt VAT),
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from 1 January 2027 – for the smallest entities, documenting sales with invoices up to PLN 10,000 per month.
The year 2026 is therefore a period of mandatory activity in the KSeF, but at the same time a "transitional" period - without financial sanctions.
KSeF 2.0, Offline Mode and Emergency Situations
One of the biggest concerns of entrepreneurs is the question: what if the KSeF system is not available at the time of sale?
The legislator has provided for several modes of operation outside the system, including:
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offline mode with sending the invoice within a specified time,
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emergency mode in case of KSeF unavailability,
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special rules for sales conducted in the field or in the absence of permanent Internet access.
Each of these methods involves different deadlines for submitting invoices to the National Securities and Financial Supervision Authority (KSeF) and other formal requirements. In many cases, QR codes and certificates identifying the issuer are also required.
These are elements that need to be planned in advance – preferably together with the IT department or accounting system provider.
Simplified invoices and exempt taxpayers – important clarifications
At the end of 2025, important clarifications regarding simplified invoices and taxpayers exempt from VAT appeared.
In particular:
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Simplified invoices issued in KSeF will have to include the issuer's Tax Identification Number,
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in the case of simplified invoices issued outside the KSeF (e.g. in consumer sales), the rules remain more flexible,
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VAT-exempt taxpayers will also be subject to the KSeF obligation if they issue invoices.
These seemingly minor changes have a huge impact on the configuration of sales and checkout systems.
Sanctions – why it is not worth postponing preparations
Although the obligation to apply the KSeF will come into force in 2026, financial penalties will only apply from 1 January 2027.
This does not mean, however, that we can "wait until 2026".
From 2027, the following are planned:
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penalties of up to 100% of the VAT amount shown on the invoice issued outside the KSeF,
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percentage penalties on the value of the receivable when the invoice does not show VAT.
Therefore, 2026 should be treated as a time to stabilize processes and eliminate errors before sanctions come into force.
Poland is no exception – where are similar systems already in operation?
The Polish KSeF is part of the European trend of digitalization of tax settlements.
Similar solutions already exist, including:
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in Italy, where e-invoicing has been mandatory for several years,
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in Romania, which introduced the obligation of e-invoicing in B2B relations,
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in Hungary, where invoices are reported to the tax administration almost in real time,
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in France, which is implementing mandatory e-invoicing in stages.
The experiences of these countries show one thing: the biggest challenge is not the technology itself, but the adaptation of processes and people.
How to prepare your company for KSeF – the minimum that is worth doing now
Before the obligation comes into force, it is worth:
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Determine from when exactly the company is subject to KSeF.
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Analyze your current invoicing process (sales, adjustments, advances, e-commerce).
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Check the readiness of accounting and sales systems.
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Sort out the issues of rights and powers of attorney in the KSeF.
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Prepare offline and emergency procedures.
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Train employees before the system becomes mandatory.
Training and consultations – support from Grażyna Janowicz
If you want to approach KSeF calmly and professionally, I invite you to use the support of Grażyna Janowicz – tax advisor and certified auditor .
The following are offered:
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training for entrepreneurs and accounting offices (KSeF from the practical side),
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individual implementation consultations,
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risk analysis and adaptation of procedures to the specific needs of the company,
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support in communication with the IT department and system suppliers.
KSeF is not just an obligation – it is a change that should be well planned.