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The revolution in documenting transactions for VAT purposes is approaching. The changes impose a huge challenge from both the technological and organizational side for most entrepreneurs.
The new regulations go much further than simply requiring taxpayers to issue invoices through the National e-Invoice System (KSeF) according to a designed structure and format. This is a change in approach to the whole procedure involved in issuing and receiving invoices.
The introduction of KSeF in Poland also forces a number of organizational changes in the structures of entire companies, the new rules of invoicing and documenting transactions are of considerable importance for the functioning of not only accounting departments, but also sales or purchasing departments, which must take into account the generally applicable VAT regulations when making arrangements with partners.
The introduction of KSeF is, on the one hand, an opportunity for audit and automation and, on the other hand, a challenge and even a threat in the absence of proper preparation.
In this guide, we present the most important information on the National e-Invoicing System hoping that it will be helpful in adapting your company’s procedures and systems to the coming revolution.
At the same time, we emphasize that the guide is prepared on the basis of the draft amendment to the regulations introducing KSeF in Poland.
The National e-Invoice System is a nationwide ICT system for issuing, sharing and storing structured invoices (i.e. so-called e-invoices). KSeF ensures the authenticity of origin, integrity of content and legibility of the structured invoice.
In simple terms, KSeF is a kind of invoice data cloud. Users of this system enter information into it in order to issue an invoice and receive invoices issued in this system by other taxpayers.
From 1 January 2022, taxpayers can voluntarily use KSeF and issue structured invoices in KSeF.
In parallel, it is possible to issue invoices in the existing form (paper or electronic).
Once the mandatory KSeF comes into force, the only acceptable form of invoicing for most transactions will be the issuing of VAT invoices via KSeF. Purchase invoices will also be received by taxpayers via KSeF.
The National e-Invoice System is primarily used for issuing, accessing, receiving and storing structured invoices. In addition, KSeF serves, among other things, to:
A structured invoice, or so-called e-invoice, should be issued using the National e-Invoice System with an assigned number identifying this invoice (so-called KSeF number).
The structured invoice will be issue in XML (Extensible Markup Language) format compliant with the logical structure of the FA(3) e-Invoice published in the Central Repository of Electronic Document Templates (CRWDE) on the ePUAP platform.
The XML format structures the data in a tree-like form made up of nested elements. This format is commonly used for transferring data in a structured form, but it is not very readable for users.
For the visualization of structured invoices, specially designed programs or appropriate upgrades to your accounting software are needed.
From when KSeF will be mandatory?
Currently, KSeF and issuing of structured invoices is voluntary.
From 1 February 2026, so-called “large” taxpayers (with sales for 2024 exceeding PLN 200 million including tax) will be required to issue structured invoices using the National e-Invoice System (KSeF).
From 1 April 2026, this obligation will extend to all entrepreneurs.
As an exception, the smallest taxpayers whose transactions involve small amounts (with total sales including tax not exceeding PLN 10,000 per month) will be covered by this obligation starting from January 1, 2027.
The obligation to invoice via KSeF will cover activities that are subject to VAT in Poland. These are: domestic supplies of goods and services between businesses (i.e. B2B) and to public authorities
(i.e. B2G).
Invoices issued to individuals not engaged in business activity (B2C) will be excluded from e-invoicing – e-invoicing of B2C transactions will be possible on a voluntary basis.
In addition, the mandatory KSeF will not apply to foreign taxpayers who do not have a permanent place of business in Poland or when such a permanent place does not participate in the documented transaction. However, they may use the KSeF on a voluntary basis.
Furthermore, the obligation to issue e-invoices via KSeF will not apply to invoices:
As indicated earlier, there will be no obligation to issue invoices to individuals using KSeF. However, if the taxpayer decides to issue invoices using KSeF to individuals, the taxpayer will be able to do so. However, the taxpayer will additionally be obliged to provide the purchaser with access to that invoice (unless the purchaser relievs the taxpayer from this obligation).
If the purchaser wishes to access that invoice in KSeF or wishes to use it outside KSeF, the vendor will have to mark the invoice with a QR code or provide the purchaser with that code and the details to identify that invoice.
Issuing of an invoice to foreign taxpayers will not be exempt from KSeF. Instead, the supply of these invoices outside KSeF will be allowed. In the event that:
the structured invoice should be made available to the purchaser in a way agreed upon with them. However, in such a case, the Polish VAT taxpayer will be required to mark the structured invoice with a QR code allowing access to it in KSeF and allowing verification of the included data.
Taxpayers
Entities designated by the taxpayer
Enforcement authorities and bailiffs and natural persons indicated by these entities
Natural persons indicated in the notice of the assigment or withdrawal of rights to use KSeF, to whom the taxpayer, enforcement authorities or bailiffs have assigned rights to use this system.
Entities other than those mentioned indicated by individuals using KSeF, if the right to indicate another entity results from the powers granted to these individuals.
Authenticated in the manner prescribed by the provisions.
In practice, KSeF can be used by any VAT taxpayer or by persons (entities) designated by the taxpayer, who will be properly authenticated, i.e. verified.
Authentication in KSeF is performed by:
ZAW-FA form
In the case of taxpayers or entities that are not individuals and do not have the ability to authenticate in one of the above ways, granting or withdrawal of entitlements to use KSeF is done by submitting a notice of granting or withdrawal of entitlements to use KSeF to the relevant head of the tax office via the ZAW-FA form.
Invoices RR (and correcting RR invoices) will operate under specific rules. These invoices will be able to be issued using KSeF, but only with the consent of the supplier (i.e. with the consent of the lump-sum tax farmer). If the farmer wishes to receive RR VAT invoices in KSeF, he will have to give his consent to do so with a specific purchaser of agricultural products. If consent is not given, RR invoices will be issued under the current rules.
It should be stressed that the entry into force of the mandatory KSeF will result in a complete change in the way of invoicing and will require a change in the approach to the process.
Taxpayers will generate and send to KSeF the data to be included on the invoice. This data will have to be in a specific form and structure (in XML format). Once KSeF receives the data and checked it for completeness and structure, it will issue an invoice and give it an identifying number (the so-called KSeF number).
This means that an invoice generated by the taxpayer that has not been sent to KSeF does not constitute a VAT invoice, but only a set of data that should be included on the invoice. Sending this set of data (in XML format) to KSeF results in KSeF issuing a VAT invoice based on the data received.
It should be emphasized that a structured invoice is deemed to have been issued on the date it is uploaded to KSeF. The date of generation or the date indicated as the date of issue when the XML file is generated is therefore not relevant.
The invoice can be sent to KSeF on the same day or the day after it is generated.
It will be possible to disclose attachments to structured invoices, but they will be an integral part of the sales document and their content will be structured and described in the FA(3) logical structure.
KSeF makes it possible to send generated invoices in two ways:
If an invoice contains errors (e.g. not all the required fields are filled in), the invoice is rejected. Similarly, when an invoice is sent to KSeF by a person without the appropriate authorization, it will be rejected too.
Taxpayers can issue e-invoices in free programmes provided by the Ministry of Finance (sufficient for a small number of invoices) or through specially prepared financial and accounting systems (useful for a large number of documents).
KSeF is not only a system for issuing invoices, but also through which they are received.
Once an invoice successfully reaches KSeF and gets its unique KSeF number, it is considered that the purchaser has received it.
KSeF does not inform taxpayers of the receipt of ‘new’ invoices. This means that taxpayers, through their software used to generate invoices, should check whether they have received a purchase invoice. To facilitate this process, the possibility of downloading invoices in bulk from KSeF is provided for, but only in XML form.
There are a number of benefits for taxpayers using KSeF. The most important are:
Simplified invoice processing and enabled automation of accounting through a standardaized XML format
Direct invoice delivery via the system with confirmation of receipt
Reduced VAT refund period – from 60 to 40 days
System-stored invoices resistant to loss or destruction
Elimination of the need to submit JPK_FA upon request from tax authorities
Storage of all invoices in KSeF for 10 years from the end of the year in which they were issued – taxpayers are no longer required to archive them manually
In the event of unavailability of KSeF, an appropriate announcement will be posted on the Public Information Bulletin indicating the duration of unavailability. During the period of unavailability of KSeF, the taxpayer will issue structured invoices according to the relevant template in XML format. These invoices will be made available not through KSeF, but in a manner agreed upon with the recipient.
Within 7 working days of the end of KSeF failure period, the taxpayer will be required to send to KSeF the invoices issued during the failure period in order to assign numbers identifying these invoices in KSeF.
In the event of a “major” failure and the inability to post messages on the Public Information Bulletin, the alerts will be posted in social media.
In the event of such a ‘major’ failure, the taxpayer will issue paper invoices or electronic invoices (e.g. in pdf format) during the period of failure.
If the taxpayer is unable to issue a structured invoice for any other reason (for reasons attributable to the taxpayer, the so-called off-line mode), the taxpayer will issue structured invoices according to the relevant template in XML format.
The taxpayer will then be obliged to send invoices issued in this way to KSeF in order to assign a number no later than the next business day after the date of issue.
If the taxpayer, contrary to the obligation:
the head of the tax office will impose on the taxpayer a fine of up to 100 % of the amount of tax shown on that invoice, and in the case of an invoice without any tax shown – a fine of up to 18.7 % of the amount of the total receivable shown on that invoice.
In the event of a taxpayer’s failure to comply with the above-mentioned obligations, no proceedings for fiscal crimes or fiscal offences will be initiated.
It should be emphasized that the penalties will only apply from 1 January 2027.
The possibility of issuing invoices in “offline24” mode has been permanently introduced. Initially, offline mode was to be a mode used only in the transitional period, until the end of 2026. The purpose of the offline mode is to facilitate compliance with obligations when the taxpayer encounters difficulties in issuing and uploading e-invoices to the system, or the specific nature of the taxpayer’s business justifies the use of this mode.
In practice, the introduction of the off-line mode means that an invoice issued according to the template can be sent to KSeF on the next business day.
Such a solution will unambiguously reduce discrepancies between the date of issue indicated on the invoice and the date of issue understood as the date of transmission to KSeF.
Purchasers of goods or services, registered as VAT taxpayers, making payments for structured invoices to other VAT taxpayers, by means of a direct debit service, a payment order, or any other payment instrument allowing the title of the funds transfer, will be obliged to provide KSeF number (or KSeF collective identifier). This obligation will also apply to taxable persons other than the purchaser of goods or services making payments for invoices issued to that purchaser.
The obligation indicated above will apply to payments made from 1 January 2027.
This means that as of 1 January 2027, the obligation to indicate KSeF number (or KSeF collective identifier) in the payment order will apply to all payments (not only those made under the split payment mechanism) for transactions made between active VAT taxpayers.
In the KSeF Application provided by the Ministry of Finance, in addition to just issuing, receiving, and viewing e-invoices or managing authorizations, it is also possible to generate a preview of an invoice without logging in (so-called anonymous access to an e-invoice).
1. Will KSeF accept invoices without optional elements (other than from the VAT Act) but resulting from the structure?
The invoice to be sent must comply with the FA(3) logical structure. If the invoice contains errors, e.g. not all the fields required by the structure are filled in, the invoice will be rejected. It should be noted that there are fields in the structure that become mandatory when filling in nodes or sequences of an optional nature, where these fields are included even though they concern elements not required by the VAT Act. In this type of situation, optionality is achieved at the node or sequence level.
Therefore, when optional nodes contained in an invoice are filled in, the mandatory fields in that node must be filled in for the invoice file to be sent effectively.
2. Will a paper invoice or pdf form be completely redundant? They will only be a courtesy from the seller to the purchaser?
Yes, the paper form of the invoice will be redundant. Currently, the purchaser can request that the invoice be provided in another way, e.g. on paper or electronically.
3. What is meant by sending an invoice? What if an invoice is not validated correctly?
Sending is to be understood as the initiation of the sending of an e-invoice within an open session. If the system rejects the invoice, it will not be sent to KSeF. In such a case, the correctness of the entered data must be verified and the dispatch must be repeated.
4. Is it possible to invoice individuals at KSeF?
Yes, KSeF provides for the possibility to issue invoices to taxable persons (B2B) as well as to individuals not engaged in business (B2C) and allows access to these invoices, inter alia through so-called anonymous access.
5. Will invoices from foreign suppliers without a Polish NIP have to be reported to KSeF?
No, KSeF is not used for reporting invoices from foreign suppliers.
6. Does the recipient get information from KSeF that an entity has invoiced them?
No. Such functionality is not envisaged, as for taxpayers receiving very large volumes of invoices this could be a hindrance rather than a convenience. In order to obtain information about available invoices, the software used by the taxable person will have to “query” KSeF.
7. Will the invoice issuer receive a KSeF number back?
Yes, KSeF number is indicated in the official confirmation of receipt (UPO).
8. Will the numbers assigned by KSeF to invoices issued have to be sent to recipients so that they can download invoices from KSeF?
No, receipt of the invoice by the purchaser does not require the purchaser to have KSeF number of the invoice. The exception is the so-called anonymous access to the invoice.
9. How does the date and time of issue of an e-invoice document relate to the date of issue field (P_1)?
The date provided in field P_1 is the date of issue indicated by the invoice issuer. On the other hand, the field DataWytworzeniaFa is only technical in nature, it is the system-generated date and time when the invoice was created.
10. Does the document have to be sent to KSeF on the day of issue?
The document can be sent the next day, with maintaining the statutory deadlines for issuing invoices. Indicating a specific date in field P_1 does not oblige the taxpayer to send an invoice to KSeF on that day.
11. May “proforma” invoices be issued in KSeF?
The so-called “proforma” is not an invoice within the meaning of the VAT Act. Therefore, the issuance of such documents is not provided for in the KSeF.
12. The invoice was sent to KSeF and was assigned a KSeF number. The seller would also like to send the purchaser a printout of this invoice. Should KSeF number always be included on the printout?
It is not necessary to include the invoice identification number in KSeF on the invoice printout.
13. How and whether to send a correction of an incorrect NIP to the purchaser?
If an invoice with an incorrect purchaser’s NIP is sent to KSeF system, in order to correct the situation, a corrective invoice “to zero” should be sent with the incorrect purchaser’s NIP and additionally should be send a separate (original) invoice with the correct purchaser’s NIP.
This results from systemic conditions. After processing, an invoice with an incorrect NIP number of the purchaser will be made available to the entity with this NIP number.
14. Is it possible to enclose attachments to the e-invoice (e.g. receipt protocols)?
It is not possible to enclose attachments to structured invoices. However, it is possible to include an appropriate link to such documentation in the content of the invoice.
Additional information can be entered in the DodatkowyOpis, DodatkoweInfo or possibly in the invoice footer. Attachments may also be sent separately outside KSeF.
15. What happens if the issuer sends an invoice with accounting errors?
The invoice will be accepted into KSeF, the system does not verify accounting errors contained in the invoice. If such errors occur, it is necessary to issue a corrective invoice.
16. Does KSeF allow rejection of an invoice in the event of an incorrectly issued invoice by the taxpayer, e.g. to the wrong purchaser?
No, in such a case the invoice issuer will be obliged to issue an invoice correction.
17. Will it be possible to download cost invoices in bulk from KSeF?
Yes, it is possible to download invoices in bulk, but only in XML form.
18. What happens if an invoice sent to KSeF is rejected? Should such an invoice be corrected and sent again? Can an invoice that has been rejected in KSeF be canceled or a correction issued?
An invoice that has been rejected is not considered issued, so it cannot be corrected or canceled. If the system rejects the invoice, it is up to the taxpayer to decide whether he wants to correct it and send it again to KSeF.
An invoice may be rejected by the system only because the file structure is inconsistent with the logical formula or because it was entered into the system by an unauthorized person.
19. Should the invoice number assigned by KSeF be stored in accounting systems?
An invoice that has been rejected is not considered issued, so it cannot be corrected or canceled. If the system rejects the invoice, it is up to the taxpayer to decide whether he wants to correct it and send it again to KSeF.
An invoice may be rejected by the system only because the file structure is inconsistent with the logical formula or because it was entered into the system by an unauthorized person.
20. Is a signature required when sending invoices or invoice packages?
Sending can be done as part of an interactive or “wsadowa” session (invoice batches). The invoice or a set of invoices will be sent by the taxpayer or an authorized person, after the user’s authorization process has been properly completed, e.g. by means of a qualified electronic signature.
21. How is the initial entitlement granted in KSeF in the case of a taxpayer who is not an individual?
In the case of taxpayers who are not individuals and have an electronic qualified stamp containing the NIP, it is possible to use KSeF based on the original ownership rights without reporting to the tax office.
In other cases, in order to use KSeF, a taxpayer who is not a n individuals must indicate, via the ZAW-FA form, a natural person authorized to use KSeF on behalf of the taxpayer. This person will also have the opportunity to grant further authorizations electronically within KSeF.
22. How to technically authorize another person to issue invoices on behalf of the taxpayer/company?
In order to enable the issuance of an invoice on behalf of an entity or other natural person conducting business activity, a dedicated authorization to issue invoices should be granted in this respect. Granting the authorization will be possible using commercial programs, as well as in KSeF web application for taxpayers prepared by the Ministry of Finance.
23. For foreign entities that operate in Poland through proxies, will these proxies be able to act on behalf of the taxpayer in KSeF and grant further powers of attorney?
A foreign entity with a Polish NIP identifier may act through a proxy. In such a case, it is necessary for this entity to submit a ZAW-FA notification, in which the entity will designate a specific natural person to use KSeF (including granting rights, withdrawing rights, issuing invoices on behalf of the entity and access to invoices).
24. If sales invoices are issued by an accounting office, do individual employees of this accounting office need to be authorized to issue invoices each time?
KSeF provides for the possibility for the taxpayer to indicate an entity authorized to issue invoices, e.g. an accounting office. In such a case, the taxpayer’s invoices may be issued by natural persons authorized to issue invoices on behalf of this entity, i.e. employees of this office.
25. At what point does granting authorization to a person enable him to be authenticated in the system? What if the ZAW-FA notice is sent by post?
For the authorization to take effect, it must be entered into the system. In the case of electronic applications, the rights will be effective immediately after the authorization is processed.
The authorization granted via the ZAW-FA notification will be entered into the system by the competent tax office, which will first verify the formal aspects of the notification, in particular whether the notification is signed by the appropriate number of persons authorized to represent it. The competent tax office will enter the notification immediately after receiving it.
If the notification is sent by post, for obvious reasons, the delay resulting from the need to deliver the parcel to the tax office should be taken into account.
ZAW-FA contains fields regarding mandatory e-mail addresses to which notifications about granting permissions will be sent.
26. Are tokens termless or expire?
KSeF does not specify the time during which the token is valid. The generated token remains valid until it is revoked by the user or until the user’s rights are revoked.
Below we present the schedule of the most important events related to the implementation of KSeF in Poland.
The mandatory implementation of the National e-Invoicing System (KSeF) is a significant catalyst for transformation in the finance and accounting function. The changes extend beyond how invoices are recorded, affecting the entire chain of responsibilities, tools, and procedures related to accounting and tax documentation.
The new model, based on a standardized XML format and centralized data transmission to tax authorities, effectively requires a redesign of internal processes to align with a highly digitized environment.
Key areas of impact include:
KSeF is a driver of digital transformation in the finance and accounting function. It enables process standardization, automation of data processing, and a reduction in compliance risk through embedded validation mechanisms within the document workflow.
Implementing the National e-Invoicing System (KSeF) requires a structured project approach encompassing both technical infrastructure adaptation and organizational and substantive readiness. The process should be executed in phases, taking into account system constraints, legal requirements, and the company’s operational specifics. Uncoordinated or delayed implementation increases the risk of errors, operational disruptions, and financial penalties.
Phase 1: Readiness Audit
Analysis of invoicing processes, IT systems, data structures, and role assignments. The goal is to identify gaps between the current state and KSeF requirements and define the scope of necessary changes.
Phase 2: Selection of Integration Model and Technology Provider
Decision on the method of integration (e.g., direct ERP integration, external module, intermediary platform) and selection of the provider or contractor responsible for implementing the KSeF component.
Phase 3: ERP System Configuration and KSeF Tool Setup
Configuration of schemas, data mappings, authentication tokens, and invoice processing logic. Ensuring the system fully supports the FA(3) structure and complies with KSeF API communication requirements.
Phase 4: Update of Internal Procedures and Documentation
Review of accounting policies, document circulation instructions, archiving rules, and control procedures. Definition of processes for handling errors, corrective invoices, and offline mode.
Phase 5: User Training
Preparation of finance, operations, and IT teams for working in the new model. Training should cover both technical and substantive aspects.
Phase 6: Integration Testing in a Demo Environment
Verification of communication with KSeF, compliance of XML structure with the FA(3) schema, accuracy of transmitted data, and continuity of the process from invoice issuance to its registration and import into the accounting system.
Phase 7: Go-Live and Post-Implementation Support
Activation of communication with KSeF in the production environment. Provision of operational support after go-live.
The introduction of a mandatory invoicing model based on the XML format and the central registration of documents in the KSeF system requires organizations to redesign their accounting processes. The key changes involve how invoices are processed, the integration with accounting systems, and the adaptation of operational workflows.
A successfully executed implementation and integration ensures not only compliance with the technical requirements of the Ministry of Finance but also enables long-term improvements in data processing efficiency.
Key implementation components include:
The implementation of KSeF enforces data standardization and the phasing out of unstructured formats in invoicing processes.
Depending on the scale of operations, system architecture, and available internal resources, organizations should consider the most effective approach for implementing the National e-Invoicing System (KSeF). In practice, different models are feasible ranging from in-house projects to engaging a specialized external partner.
The choice of an operational model should consider both implementation efficiency and the ability to further develop the system in a dynamic regulatory environment.
The scope and method of KSeF implementation should be aligned with the organization’s structure, process characteristics, and availability of technological and operational resources. In many cases, involving an external partner with proven experience in integrating financial and accounting systems is an effective approach.
The selected implementation model should be preceded by an assessment of operational risks, internal capabilities, and a realistic project timeline. From a compliance perspective, it is critical that the chosen solution ensures scalability, data security, and integrity between the financial system and KSeF.
A team of tax advisors and technology experts supports organizations throughout each phase of the implementation process:
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