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KSeF in Poland: Complete compliance guide | eBook

November 17, 2025

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 emphasise that the guide has been updated in accordance with the latest version of the regulations introducing the National e-Invoice System, or KSeF 2.0, into the Polish legal system.

If necessary, we will be pleased to provide detailed information on all matters related to KSeF and assist you in preparing for the upcoming changes.

Download our guide on KSeF in Poland, or read more below:

KSeF in Poland – Key information

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:

  • granting, changing or withdrawing rights of use of KSeF
  • notifying entities authorized to use KSeF of granting or revoking of rights to use KSeF
  • authentication and verification of rights to use KSeF
  • marking structured invoices with an identification number assigned in KSeF
  • verification of data from structured invoices used outside KSeF
  • analyzing and controlling correctness of data from structured invoices.

What is a structured invoice and from when KSeF will be mandatory

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?

Until the mandatory KSeF comes into force, issuing 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 a total sales value including tax documented by invoices issued in a given month up to PLN 10,000) will be covered by this obligation starting from January 1, 2027.

Note: From 1 February 2026, all taxpayers will be required to receive invoices issued by so-called ‘large’ taxpayers in KSeF (also if they themselves are required to issue invoices in KSeF from 1 April 2026 or 1 January 2027).

For which transactions KSeF will be mandatory

The obligation to invoice via KSeF will cover activities that are subject to VAT in Poland. These are: 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:

  • so called simplified (the total amount due does not exceed PLN 450 or EUR 100)
    – until the end of 2024
  • issued with the cash register – until the end of 2024
  • for the toll motorway (in the form of a single ticket) – on the basis of the draft regulation
  • for the carriage of persons over any distance: on normal railways, motor rolling stock, seagoing vessels, inland and coastal waterway means of transport, ferries, aircraft
    and helicopters (in the form of a single ticket) – on the basis of a draft regulation
  • for services exempt under Article 43(1)(7) and Articles 37–41 of the VAT Act – based on the draft regulation
  • for the supply of goods or services documented by invoices issued by the purchaser under the self-invoicing procedure:
    • if the purchaser is not identified for the purposes of the transaction by means of a Polish tax identification number (NIP) or
    • if the seller is not identified for the purposes of the transaction by means of a Polish tax identification number (NIP)
  • – based on the draft regulation in the field of air traffic control and supervision, for which route charges are levied
  • (with the exception of services subject to a 0% VAT rate) documented by invoices issued
  • on a monthly basis by the Central Route Charges Office (CRCO) of the European Organisation for the Safety of Air Navigation (EUROCONTROL) on behalf of the Polish Air Navigation Services Agency – based on the draft regulation.

Invoices for individuals

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.

Invoice to foreign taxpayers

Issuing of an invoice to foreign taxpayers will not be exempt from KSeF. Additionally, the seller will be obliged to provide the purchaser with an invoice in a manner agreed with them (for example, they will be able to send a visualisation of the invoice marked with appropriate QR codes in the form of a PDF file).

aser 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.

Providing invoices outside KSeF

In certain cases, the seller will be required to issue a structured invoice in KSeF and additionally provide the purchaser with the issued invoice in a manner agreed with them (for example, the seller will be able to send a visualisation of the invoice in the form of a PDF file).

Providing the purchaser with an e-invoice in a manner agreed with them will be mandatory when:

  1. the place of supply is the territory of a Member State other than the territory of Poland or the territory of a third country, or
  2. the purchaser is an entity that does not have its registered office or permanent place of business in the territory of the country, or
  3. the purchaser is an entity without a registered office in the country, which has a permanent place of business in the country, but this permanent place of business is not involved in the purchase of the goods or services for which the invoice was issued, or
  4. the purchaser is a taxpayer benefiting from the exemption referred to in Article 113a(1) (SME procedure), or
  5. the purchaser is an entity that does not use a VAT number, or
  6. the purchaser is a natural person not engaged in economic activity

If an e-invoice is made available outside KSeF, the VAT taxpayer will be required to mark such a visualisation of a structured invoice with QR codes enabling access to it in KSeF and enabling verification of the data included.

Who may use KSeF

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:

  • a qualified electronic signature
  • a qualified electronic seal (the equivalent of a qualified electronic signature for companies)
  • a trusted signature
  • KSeF certificate
  • a string of alphanumeric characters generated by KSeF, excluding punctuation marks, assigned to a taxpayer or an authorized entity and its authorizations (the so-called Token) – only until the end of 2026
  • and verification of the rights held.

ZAW-FA form

In the case of taxpayers or entities that are not individuals and do not have the ability to authenticate by a qualified electronic seal it is necessary to submit a ZAW-FA notification indicating one natural person who will be granted full rights in KSeF. This person will be able to grant further authorisations electronically in KSeF.

The natural person indicated in ZAW-FA may be any natural person – they do not have to be a natural person representing a given entity (e.g. according to the entry in the National Court Register).

VAT RR invoices

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.

Invoicing in KSeF

Sale invoices

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.

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. Attachments may only contain data on units of measurement and quantities (numbers) of goods delivered or services provided, or net unit prices.

Attaching attachments to structured invoices will require submitting an appropriate notification to the Head of the National Tax Administration.

It will not be possible to use attachments to convey information of a typically commercial, marketing or purely business nature.

KSeF makes it possible to send generated invoices in two ways:

  1. so-called wsadowa (sending several e-invoices at once)
  2. so-called interaktywna (sending a single e-invoice).

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).

Purchase invoices

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.

Benefits of using KSeF

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 

Offline24 mode

The possibility of issuing invoices in ‘offline24’ mode has been introduced. Initially,  the offline mode was to be used only during the transition period, until the end of 2026. The purpose of the offline mode is to facilitate the fulfilment of obligations when a taxpayer encounters difficulties in issuing  and sending e-invoices to the system or the specific nature of the taxpayer’s activity justifies the use of this mode.

In practice, the introduction of the offline24 mode means that an invoice issued in accordance with the template can be sent to KSeF on the next business day.

In this mode, the date of issue of structured invoices will be the date indicated by the issuer in field P_1 of the logical structure of the e-invoice, even if the e-invoice is sent to KSeF on the next working day. The date of receipt of an invoice in offline24 mode will generally be considered to be the date on which the invoice identification number is assigned in KSeF.

KSeF failures and breakdowns

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.

In the event of a KSeF failure, an appropriate announcement about the occurrence and end of the failure will be posted in the Public Information Bulletin.

During the failure period, it will be necessary to issue invoices structured in accordance with the relevant template in XML format. These invoices will not be made available via KSeF, but in a manner agreed 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.

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.

Penalties

If the taxpayer, contrary to the obligation:

  • fails to issue an invoice using KSeF,
  • will issue an invoice in electronic form during KSeF failure period not in accordance
    with the template provided,
  • fails to send an invoice (issued during the failure period) to KSeF on time

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.

Payments with KSeF number

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.

Invoice preview

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).

Q&A

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 may be sent on the next working day – it will then be considered issued offline24 mode. Indicating a specific date in field P_1 does not oblige the taxpayer in offline24 mode to send the invoice to KSeF on that date.

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 possible to enclose attachments to e-invoices. Attachments may include information on units of measurement and quantities (numbers) of goods delivered or services performed, or net unit prices.

Attachments to e-invoices are part of the invoice sent in a structured format (xml). Attachments to e-invoices may not contain other data or files in pdf or jpg format.

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?

In the case of a seller, it is necessary to store KSeF number due to the requirement to provide it in any correction invoices issued. In the case of the purchaser, the regulations do not impose such an obligation, but when making a payment for an e-invoice, it will be necessary to include the KSeF number in the transfer message (from the beginning of 2027).

There are no additional obligations related to reporting KSeF numbers..

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.

However, all tokens will remain valid until the end of 2026. After this date, it will no longer be possible to authenticate using tokens.

Schedule of events with KSeF

Below we present the schedule of the most important events related to the implementation of KSeF in Poland.

  • IIQ 2025 – Publication of FA(3) logical structure and KSeF 2.0 API documentation
  • IIIQ 2025 – Completion of legislation and testing of KSeF 2.0 API
  • IVQ 2025 – Release of test version of KSeF 2.0 Taxpayer Application.
  • 02.2026 – Start of mandatory KSeF – stage I
  • 04.2026 – Start of mandatory KSeF – stage II.

KSeF implementation in the company

KSeF as a catalyst for change in the finance and accounting function

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:

  • Redesign of invoicing processes
    Traditional mechanisms have relied on various formats and channels for document exchange. KSeF requires full data compliance with the logical schema, eliminating the use of unstructured formats.
  • Operational transformation
    The implementation of KSeF necessitates the configuration of data mappings, logical validations, and modifications to automated document posting processes.
  • Changes in interdepartmental collaboration
    KSeF implementation demands the alignment and formal integration of activities performed across departments into a unified invoicing process.

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.

Effective KSeF implementation – a phased approach

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.

Standardization and automation of accounting processes in the KSeF environment

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:

  • Integration with the financial and accounting system – support for the FA(3) structure, automatic import of documents from KSeF, and linking them to appropriate accounting and approval workflows.
  • Configuration of mappings and postings – definition of rules for assigning invoice items to general ledger accounts, cost centers, internal orders, and projects.
  • Formal and technical data validation – verification of XML structure compliance, accuracy of contractor identification data, and consistency of amounts and VAT rates.
  • Registration of purchase invoices – automated retrieval and posting of cost invoices submitted via KSeF.

The implementation of KSeF enforces data standardization and the phasing out of unstructured formats in invoicing processes.

Implementation Model

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:

  • We help select a solution aligned with your systems and operating model, taking into account existing infrastructure and invoicing practices
  • We tailor the scope of support, from end-to-end project delivery to advisory services in selected areas such as data preparation, technical testing, or user training
  • We provide operational assistance during and after implementation, including technical and functional consulting as well as ongoing support in response to regulatory changes.
Marcin Pezowicz
Process Improvement and Automation Manager | Accace Poland
Get in touch with us
Marcin Szczerbiński
Tax Supervisor | Accace Poland
Get in touch with us
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