KSeF after 1 April 2026: what to do before 1 January 2027

Since 1 February 2026, every taxpayer receives structured invoices through the National e-Invoicing System (KSeF), even if they do not yet have to issue documents in it themselves. From 1 April 2026, the obligation to issue invoices covered most businesses. Some of them, however, rely on transitional arrangements that expire on 31 December 2026, and for them the next three months are the last calm period to prepare.

The information below is general. Confirm the scope of the obligation for a specific transaction with your accountant or tax adviser.

What KSeF 2.0 is

The National e-Invoicing System is the tax administration's IT system for issuing, receiving and storing structured invoices. A structured invoice is a data file that follows the logical structure and is sent to the system. An ordinary PDF sent by email is not such a document.

On 1 February 2026, KSeF 2.0 was launched and the previous version of the system was switched off. From that day the FA(3) logical structure applies. Once a valid document is submitted, the system assigns it a KSeF number and stores the invoice for 10 years, counting from the end of the year in which it was issued. A PDF can be a readable visualisation of the invoice, but in a transaction covered by the obligation it does not replace the structured document.

What already applies under KSeF 2026

The rollout took place in stages:

• from February 1, 2026 the obligation to receive invoices in KSeF covered all taxpayers, and the obligation to issue them covered taxpayers whose sales including tax exceeded PLN 200 million in 2024;
• from April 1, 2026 the obligation to issue invoices covered the remaining taxpayers, with statutory exceptions and transitional arrangements.

The current stages are published by the Ministry of Finance on the website Implementation stages KSeF.

The obligation does not apply to every invoice. Outside KSeF remain, among others, invoices issued to consumers, i.e. individuals not running a business, invoices issued by taxpayers without a registered office or fixed place of business in Poland, and selected transactions such as travel tickets or motorway tolls. You will find the full list in the section Scope of mandatory KSeF.

Exceptions that apply until the end of 2026

Three transitional arrangements apply until 31 December 2026, and they are worth knowing because these are the ones that expire:

• PLN 10,000 limit: taxpayers may issue electronic or paper invoices outside KSeF if the total value of sales including tax documented with such invoices in a given month does not exceed PLN 10,000;
• cash registers: invoices issued using cash registers may be electronic or on paper;
• receipts with a NIP (tax ID): a fiscal receipt showing the buyer's NIP for up to PLN 450 or EUR 100 may still be treated as a simplified invoice.

If your business uses any of these exceptions, from 1 January 2027 it must issue these documents in KSeF.

What changes on 1 January 2027

From 1 January 2027 the transitional periods end, so invoices covered by the exemptions until then will have to be issued in KSeF. This mainly affects the smallest businesses that used the PLN 10,000 limit and businesses issuing invoices from cash registers. Invoices for consumers still do not have to be issued in KSeF.

The second change concerns penalties. According to the rules described by the Ministry of Finance in the material KSeF rules and legal provisions between 1 February and 31 December 2026, no financial penalties are imposed for errors in using KSeF; they apply from 1 January 2027. They cover, among other things, failing to issue an invoice in KSeF and failing to submit an invoice issued in offline24 mode on time.

On 16 September 2026 the Ministry of Finance announced an extension of the deferral of penalties to 31 December 2027. The change requires an amendment to the act, and the ministry has only just started work on the draft. According to the announcements available on 10 October 2026, this is still an announcement, not law in force. The ministry also stresses that deferring penalties does not release anyone from the obligation to use KSeF.

Offline24 mode, unavailability and total failure

The regulations distinguish several situations that are commonly called a “KSeF failure”, and each has different rules:

Situation	When	Deadline for submitting the invoice to KSeF
Offline mode24	Problems on the taxpayer's side, e.g. with the internet connection; it can also be used routinely	Without delay, no later than the next business day
KSeF unavailability	Unavailability announced in the ministry's public information bulletin	Within 7 business days of the end of the unavailability
Total failure	Announced in the mass media	Invoices are not submitted to KSeF afterwards

An invoice issued offline and given to the buyer before it is submitted to KSeF must carry two QR codes. The second confirms the issuer's identity and requires a type 2 KSeF certificate. Details are described on the page Offline mode24.

The company procedure should specify who decides on using the appropriate mode, how to generate the required QR codes, when to give the document to the buyer, who is responsible for submitting the invoice later and how to detect a document that has not been accepted.

KSeF permissions, tokens and certificates

From an IT perspective, KSeF is above all an access system. Before the end of the year, check three things.

Permissions. Establish who can issue, receive and view invoices, and who grants further permissions. Do not use shared access for several employees. Keep a register of granted permissions and have a procedure for revoking them after a change of role or the end of cooperation, including with an accounting firm or an external IT technician.

Tokens. A token is generated by a person with the appropriate permissions after authenticating in the system, and it carries the scope of permissions set when it was created. Tokens were originally meant to work until the end of 2026, but under a decision by the Ministry of Finance, this authentication method will be retained indefinitely. A token does not expire on its own until someone revokes it, so the list of active tokens should be part of your access review.

KSeF certificates. A type 1 certificate is used to authenticate in the system, and a type 2 certificate to mark offline invoices with a code confirming the issuer's identity. A certificate is valid for a maximum of 2 years, so its renewal needs to go in the administrator's calendar. Since February 2026, a certificate can be obtained in the KSeF 2.0 Taxpayer Application and through the KSeF 2.0 API.

When an ERP integration runs on a token or certificate issued to a specific person, that person leaving the business can stop invoices from being sent. We described how to put such access in order when changing IT support in the article on taking over administration.

Three ways to work with KSeF

Free tools of the Ministry of Finance

They may be enough for a simple process and a small number of documents. Assess their usefulness in practice, taking into account the time spent entering data manually, handling corrections, receiving purchase invoices and covering for an absent employee.

There is no universal number of invoices at which this solution stops making sense. The threshold depends on the complexity of the documents and the business's process.

Invoicing program with KSeF support

It may suit a business that needs smoother issuing and receiving of invoices but does not require integrated warehouse management, production or advanced accounting. Before choosing, check the range of supported documents, offline modes, permission management, data export and vendor support.

ERP system with KSeF integration

ERP can link an invoice to the order, the warehouse release, settlements and accounting. Such a project makes sense when the business needs a broader overhaul of its processes and sending the file to KSeF is only one of the requirements.

KSeF alone is not a sufficient reason to buy an extensive ERP. Precede the decision with an analysis of requirements, costs, data migration and maintenance. We describe the signs that justify such a project in our article on when to implement ERP.

What to verify in current firmware

A sales claim that “we support KSeF” is not enough. Ask the vendor detailed questions:

• Does the software support FA(3) and all document types used by the company?
• How does it show that a document has been rejected, and who receives the alert?
• How does it handle corrections, attachments and offline24 mode, including QR codes?
• Does it collect purchase invoices and prevent double posting? How does
• How does it store tokens and certificates, the KSeF number and the communication history?
• Does it remind you of an expiring certificate?
• How does it distribute user permissions?
• What does data export and the supplier change procedure look like?
• Who is responsible for updates after a schema or API change?

Confirm the scope and licence terms of each product, including enova365, in the vendor's current offer. Do not assume that all KSeF features are available in every configuration or without additional work.

A plan to prepare your business before 1 January 2027

1. Establish whether you use any of the exceptions. Check whether some of your sales go outside KSeF under the PLN 10,000 limit, from cash registers or on receipts with a NIP. These are the documents that have to be moved into the system.
2. Describe your current workflow. Identify who creates, approves, sends, receives and books invoices.
3. Carry out an access review. A list of permissions, active tokens and certificates with their expiry dates. Revoke the access of people who no longer work with the business.
4. Choose or verify your tool. Compare features, integrations, cost, support and the ability to export data.
5. Prepare exception scenarios. A rejected invoice, no internet, an announced KSeF unavailability and an absent employee. Obtain a type 2 certificate if you intend to issue invoices offline.
6. Test the integration. Check not only a valid document, but also incorrect data, a correction and a retried operation.
7. Agree the process with your accounts team. Especially receiving documents, posting, corrections and period close. We have described how we work with accounting firms that serve many clients on the page IT for accounting firms.
8. Train the users. The manual should show normal operation and error handling.
9. Monitor the first periods. Check that all documents have reached the expected status.

Frequently asked questions

Does KSeF apply to sole proprietorship?

Being a sole trader does not in itself exempt you from KSeF. What matters is your taxpayer status, the type of transaction and the exceptions in force. If you use the PLN 10,000 limit, the obligation to issue invoices in KSeF will apply to you from 1 January 2027.

Is it still possible to send a PDF to the client?

A PDF can be an additional visualisation, but in a transaction covered by mandatory KSeF it does not replace the structured invoice. How the document is delivered also depends on the buyer's status and the type of transaction.

Will penalties for KSeF errors apply from 2027?

Under the current regulations, yes, from 1 January 2027. The Ministry of Finance has announced that this date will be moved to 31 December 2027, but this requires an amendment to the act, and work on it has only just begun. Plan your preparations as if the statutory date applies.

Does KSeF replace archives and copies of accounting data?

KSeF stores invoices for 10 years, but the business still needs continuity of its own processes, related data, configuration and documents that do not go into KSeF. Agree the scope of backups with your accounts team and the system administrator.

KSeF implementation in enova365

As an Authorized enova365 Partner, we implement enova365 with KSeF integration after analysing the process: from permissions and certificates to offline mode and testing with the accounts team. If you use a different program, we can assess your current solution and prepare a plan for the last quarter of 2026.

Sources

• Ministry of Finance, Implementation stages KSeF, https://ksef.podatki.gov.pl/etapy-wdrozenia-ksef/ (accessed 10/10/2026)
• Ministry of Finance, Scope of mandatory KSeF, https://ksef.podatki.gov.pl/informacje-ogolne-ksef-20/zakres-obowiazkowego-ksef/ (accessed 02/10/2026)
• Ministry of Finance, KSeF rules and legal provisions, https://ksef.podatki.gov.pl/ksef-news/zasady-obowiazywania-ksef-i-przepisy-prawne/ (accessed 10/10/2026)
• National Revenue Administration (KAS), Extension of the deferral of penalties for errors in using KSeF to the end of 2027, 16.09.2026, https://www.gov.pl/web/kas/przedluzenie-odroczenia-kar-za-bledy-w-stosowaniu-ksef-do-konca-2027-r (accessed 10/10/2026)
• Ministry of Finance, Offline mode24, https://ksef.podatki.gov.pl/informacje-ogolne-ksef-20/tryb-offline24/ (accessed 02/10/2026)
• Ministry of Finance, KSeF certificates, https://ksef.podatki.gov.pl/informacje-ogolne-ksef-20/certyfikaty-ksef/ (accessed 10/10/2026)
• Ministry of Finance, FA(3) logical structure, https://ksef.podatki.gov.pl/informacje-ogolne-ksef-20/struktura-logiczna-fa-3/ (accessed 02/10/2026)

As of 2 October 2026. We rechecked the implementation stages, penalties, tokens and the announced penalty deferral on 10 October 2026.