Legal status and public guidance updated as of 21 April 2026.
This material is for informational and practical purposes only. It does not replace individual tax advice tailored to a specific factual situation.
Mandatory KSeF does not apply to all taxpayers and all documents in exactly the same way. Today, the key issue is to correctly distinguish between B2B and B2C sales, verify the applicable implementation dates, and identify the relevant exceptions and transitional periods.
Key takeaways
- As a rule, mandatory KSeF applies to B2B invoices issued by entities that are required to issue invoices in Poland, including taxpayers exempt from VAT.
- The rollout has been divided into stages: from 1 February 2026 for the largest taxpayers, from 1 April 2026 for other entities, and from 1 January 2027 for the smallest taxpayers with monthly invoiced sales not exceeding PLN 10,000 gross.
- Invoices issued to consumers (B2C) are not covered by mandatory KSeF. Issuing them through the system remains optional.
- Until the end of 2026, certain documents remain outside mandatory KSeF, including invoices issued using cash registers and receipts with a tax identification number (NIP) up to PLN 450 that qualify as simplified invoices.
- The year 2026 is a transitional period – penalties for errors related to the use of KSeF are expected to start applying only from 1 January 2027.
Who mandatory KSeF applies to and from when
The legislator introduced KSeF in stages. The legal form of the business itself is not decisive here – the obligation may apply to companies, sole proprietors, foundations, associations, and other entities if they issue invoices subject to Polish VAT invoicing rules.
Taxpayers whose gross sales for 2024 exceeded PLN 200 million
The obligation to use KSeF has applied since 1 February 2026 and covers invoices governed by the VAT Act.
Other businesses and other entities issuing invoices in Poland
The obligation to use KSeF has applied since 1 April 2026 and, as a rule, also covers taxpayers benefiting from VAT exemption.
Taxpayers whose monthly sales documented by invoices do not exceed PLN 10,000 gross
They may remain outside mandatory KSeF until the end of 2026. If the threshold is exceeded in 2026, the obligation arises starting with the invoice by which the threshold was exceeded.
Sales to consumers (B2C)
These are not covered by mandatory KSeF. Issuing B2C invoices through the system remains voluntary.
Foreign taxpayers with no registered seat and no fixed establishment in Poland
They are not covered by the obligation under the standard rules, but they may use KSeF voluntarily.
Does KSeF cover all transactions?
No. KSeF applies to structured invoices, not to every document used in business practice.
- Documents outside KSeF include, among others, pro forma invoices, internal documents, debit and credit notes, and other documents that are not invoices within the meaning of the VAT Act.
- Implementing regulations have also excluded certain special categories of documents treated as invoices, for example certain tickets, selected motorway services, and selected financial and insurance services.
The most important exceptions to the KSeF obligation
Subject-related exclusions
In particular, taxpayers with neither a registered seat nor a fixed establishment in Poland remain outside mandatory KSeF. The exclusion also covers situations where a taxpayer has a fixed establishment in Poland, but that establishment is not involved in the specific supply of goods or services documented by the invoice.
Object-related exclusions
Implementing regulations provide exclusions for certain documents and sectors, especially where issuing a standard structured invoice would be unreasonable or technically difficult.
Transitional periods
Until 31 December 2026, businesses may still issue invoices outside KSeF using cash registers, including receipts with a NIP up to PLN 450 treated as simplified invoices. This is particularly important for retail, hospitality, and sectors with a large number of cash register transactions.
Sales to individuals (B2C)
Sales to consumers are not covered by mandatory KSeF. B2C invoices may be issued through the system voluntarily, but there is no obligation to do so.
Practical conclusion: if the buyer is an individual not conducting business activity, the seller may generally continue to document the sale under the existing rules. A consumer's request for an invoice does not automatically create an obligation to issue it through KSeF.
The same rules apply where an individual who runs a business purchases goods or services for private purposes. If the transaction is not B2B in nature, there is no obligation to issue the invoice through KSeF.
Cash register and invoices issued to receipts
- Receipts with a NIP up to PLN 450 remain simplified invoices outside mandatory KSeF until the end of 2026.
- Invoices issued using cash registers may be issued outside KSeF until the end of 2026.
- Issuing an invoice to a consumer after a sale recorded on a cash register does not in itself mean that KSeF must be used.
Offline mode, system unavailability, and failure
The regulations provide emergency procedures for technical issues. In practice, it is worth preparing a short internal procedure specifying who issues an invoice in offline mode, who is responsible for sending it to the system afterwards, and how the deadline for submission is monitored.
Offline24, for example no internet connection
The invoice may be issued outside the system and should be sent to KSeF no later than the next business day.
KSeF unavailability officially announced by the Ministry of Finance
Invoices may be issued outside KSeF under special rules, and they should be transmitted to the system no later than the next business day after the unavailability ends.
KSeF failure officially announced by the Ministry of Finance
The invoice is delivered to the counterparty outside KSeF and then submitted to the system within 7 business days after the failure ends.
Penalties and risks
The year 2026 is a transitional period. According to public guidance from the Ministry of Finance, penalties are not imposed during this period for errors related to the use of KSeF.
From 1 January 2027, financial penalties are expected to begin applying. They may amount to up to 100% of the tax shown on an invoice issued outside KSeF, or – where no tax is shown on the invoice – up to 18.7% of the total amount due.
The most common practical risks include:
- incorrect classification of a sale as B2C instead of B2B, or vice versa,
- assuming that a VAT-exempt taxpayer is not subject to KSeF,
- incorrect calculation of the PLN 10,000 monthly threshold,
- lack of an offline and failure procedure,
- lack of proper information flow between sales, accounting, and IT.
How to prepare your company for KSeF
- Divide sales into categories: domestic B2B, B2C, cross-border sales, and sales recorded on cash registers.
- Determine whether the company can use the transitional PLN 10,000 monthly threshold.
- Set permissions, roles, and responsibilities for KSeF handling.
- Verify the readiness of the invoicing software, accounting system, and integration with JPK_VAT.
- Prepare an internal procedure for no internet access, system unavailability, and system failure.
- Train staff in sales, accounting, and customer service teams.
Practical examples
A psychotherapy practice benefiting from VAT exemption
If it issues invoices to businesses and does not fall within the transitional PLN 10,000 monthly threshold, it must, as a rule, use KSeF. VAT exemption alone does not remove the obligation.
A retail store selling to private individuals
Retail sales recorded on a cash register do not automatically trigger the KSeF obligation. B2C invoices remain voluntary, and invoices issued from cash registers may remain outside KSeF until the end of 2026.
A small service business issuing three invoices per month for PLN 2,000 each
It may remain outside mandatory KSeF until the end of 2026, because the monthly value of sales documented by invoices does not exceed PLN 10,000 gross.
A Polish company issuing an invoice to a contractor outside the EU
If the transaction is subject to Polish invoicing rules and no statutory exclusion applies, the invoice may fall within KSeF and then be delivered to the buyer in an agreed form outside the system.
Final conclusions
The safest assumption is that mandatory KSeF primarily concerns domestic B2B transactions, as a rule also covers VAT-exempt taxpayers, but does not mandatorily cover sales to consumers.
For businesses, what matters today is not only knowing the implementation dates, but also correctly distinguishing between covered and excluded transactions, properly calculating the transitional thresholds, and preparing the organization for emergency situations.
From a management perspective, 2026 should be treated as an implementation period – a time to organize processes, system integrations, and internal responsibilities before real penalties start to apply in 2027.
Basis of preparation and sources
- KSeF Portal – “Scope of mandatory KSeF”.
- KSeF Portal – “What is worth knowing before the start of the second stage of implementing the National e-Invoicing System”.
- KSeF Portal – “Consumers and individuals”.
- KSeF Portal – “KSeF 2.0 questions and answers”.
- KSeF Portal – “Implementing regulations for the National e-Invoicing System”.
- gov.pl – announcement: “Second stage of implementing the National e-Invoicing System”.
- Act of 16 June 2023 amending the Act on tax on goods and services and certain other acts, together with subsequent acts amending the KSeF implementation schedule.