Briefing document & Podcast: Poland E-Invoicing, E-Reporting and KSeF Mandate

Last update: October 20, 2025

Here’s a briefing document summarizing the key information from the provided sources regarding the Polish KSeF e-invoicing mandate:

Mandatory E-Invoicing in Poland (KSeF) – Overview & 2026 Implementation

Legal Framework and Mandate Overview

• From 1 February 2026: “Large taxpayers” – defined as businesses with 2024 sales exceeding PLN 200 million gross (incl. VAT) – must issue all invoices electronically via KSeF. This captures Poland’s largest companies (approximately those with >€45M turnover). Notably, all VAT-registered businesses must be ready to receive e-invoices via KSeF by this date, even if they are not yet obliged to issue them. In practice, this means medium and small companies should be capable of retrieving invoices from KSeF starting Feb 2026, because large suppliers will only use KSeF to send invoices. [kpmg.com], [hlb-poland.global] [rtcsuite.com], [theinvoicinghub.com]
• From 1 April 2026: The mandate extends to all other VAT payers – i.e. medium and small enterprises – except the very smallest. All active VAT taxpayers (and even VAT-exempt businesses) must use KSeF for invoicing from this date, excluding “micro-businesses” meeting a low sales threshold. The excluded group is defined as taxpayers whose monthly invoiced sales in 2026 do not exceed PLN 10,000 gross (~€2,300). This carve-out spares businesses that issue only a handful of invoices (e.g. very small sole proprietorships) from immediate compliance. [kpmg.com], [hlb-poland.global]
• From 1 January 2027: Micro-businesses (those below the PLN 10k/month invoicing threshold in 2026) will enter KSeF from the start of 2027. At this point, KSeF becomes universal for all entities conducting business in Poland. The staged timeline was designed to mitigate disruption: larger firms lead the adoption, while the smallest get nearly an extra year to prepare. [kpmg.com], [hlb-poland.global] [hlb-poland.global]

• Domestic B2B invoices: All invoices between Polish companies (or Polish VAT-registered entities) for transactions within Poland fall under KSeF. Once mandatory, a structured e-invoice on KSeF will be the only valid form of invoice for B2B transactions. Traditional paper or PDF invoices will no longer be accepted for VAT accounting (outside of contingency situations) – maintaining an audit trail via KSeF will be legally required for VAT compliance. [theinvoicinghub.com], [theinvoicinghub.com]
• B2G (Business-to-Government) invoices: Invoices issued to public sector entities are included. Poland already required public administrations to accept e-invoices (since April 2019, via the separate PEF platform using Peppol BIS 3.0 format). From 2026, this is unified: suppliers must send structured invoices to government bodies through KSeF (FA(3) format) as the primary channel. Public entities will adapt to retrieve invoices from KSeF (the KSeF system is expected to connect with the Peppol network as well, to facilitate cross-platform interoperability). During the transition, government buyers can accept invoices either via the old PEF/Peppol route or the new KSeF route, but by 2026 all public authorities will be on KSeF for incoming invoices. [theinvoicinghub.com] [theinvoicinghub.com], [theinvoicinghub.com]
• Exports and Cross-Border B2B invoices: The law covers invoices issued by Polish taxpayers for cross-border or foreign transactions as well. For example, if a Polish company sells goods or services to a business abroad, it still must generate a KSeF e-invoice (even if that invoice is zero-rated for VAT). The foreign customer, however, is not on the KSeF platform, so the Polish supplier is allowed to deliver a copy of the invoice to the foreign buyer by other means (email, etc.). The KSeF system in that case serves an e-reporting function – the invoice is recorded and stored centrally for Polish VAT purposes, but the commercial exchange of the invoice with the non-Polish customer can occur outside the system (see “Cross-Border Transactions” below for details on how such scenarios are handled). [rtcsuite.com], [theinvoicinghub.com] [rtcsuite.com], [rtcsuite.com]
• B2C (Business-to-Consumer) invoices: Invoices issued to private individuals (consumers) are not strictly mandated to go through KSeF under the new law. In Poland, retail sales to consumers are typically documented via fiscal cash register receipts (paragons), not formal VAT invoices unless a consumer specifically requests one. The KSeF regulations clarify that consumer invoices may be issued in KSeF, but this is optional – paper or electronic receipts/invoices will remain allowed for B2C. Moreover, the law explicitly permits certain invoices to be issued outside KSeF through 2026 in defined cases, one of which is invoices generated by cash registers (fiskalny receipts that serve as invoices up to a certain amount). Thus, a store can continue to give a regular receipt to consumers in 2026. However, if a consumer does request an invoice (with their personal details), the business can either issue it via KSeF or on paper – Poland’s Ministry of Finance has indicated that B2C will not be forced into KSeF because individuals do not have VAT IDs to access the system easily. By allowing but not requiring consumer e-invoices, Poland balances digital reporting aims with practical considerations for retail. (In practice, we expect most high-volume consumer transactions to remain handled by receipts, not KSeF invoices, at least initially. KSeF does include fields for consumer invoices and the law allows them in KSeF, so some businesses may trial sending B2C invoices through KSeF once the system is stable.) [theinvoicinghub.com] [kpmg.com], [hlb-poland.global] [kpmg.com], [theinvoicinghub.com] [kpmg.com]

• Small-amount invoices and micros (2026 only): As noted, taxpayers whose monthly invoicing is under PLN 10k can continue using existing invoicing methods through 2026. Also, invoices under PLN 450 (simplified invoices) might still be handled via cash register receipts for that period. After the grace period, these will have to be reported into KSeF (e.g. via integration of cash registers with KSeF by 2027). [hlb-poland.global] [theinvoicinghub.com], [theinvoicinghub.com]
• Certain one-off documents: Some documents like postal service invoices (bills of postage) and VAT RR invoices (special invoices for agricultural purchases) initially were not supported in KSeF. The new law, however, allows VAT RR invoices to be issued in KSeF from 1 April 2026 onward. For other atypical documents, the Ministry has provided either temporary exemptions or alternative handling. Many such niche cases (e.g. tickets that serve as invoices) will continue to be regulated by separate provisions until KSeF functionality covers them. [kpmg.com]
• Self-billing transactions with foreign parties: In a self-billing scenario, the buyer issues an invoice on behalf of the supplier. If one of the parties is foreign and does not have a Polish tax ID (NIP), the invoice will not go through KSeF. Draft executive rules confirm that if, for example, a foreign customer without a Polish NIP self-bills a Polish supplier, or a Polish buyer self-bills a foreign supplier without Polish NIP, those invoices can be exchanged traditionally (outside KSeF). This is because KSeF requires both issuer and recipient to be identified in the system (typically by NIP/VAT number). In absence of a Polish identifier, the system cannot fully process the invoice. These cases are relatively rare, but it ensures that international self-billing or commissionaire arrangements aren’t disrupted – such invoices will simply be handled as they are today (PDF or paper), and the Polish party will account for VAT via existing rules. [rtcsuite.com]
• Continuous transactions straddling the go-live date: For practical implementation, if an invoice was issued before the mandate (e.g. in January 2026) it remains valid even if received after Feb 1. Only invoices issued on or after the mandate effect date must use KSeF. Also, if a contract or system issues invoices for past periods, businesses may need to transition open invoices into KSeF to avoid overlap. The law’s transitional provisions aim to avoid penalizing invoices issued just around the cutover, and the no-penalty period in 2026 gives leeway for any accidental non-KSeF invoices in the initial months (see “Implementation Timeline & Transition” below).

Technical Standards and KSeF System Features

• Structured Invoice Format (FA(3)): All invoices in KSeF must be issued in a standard XML format known as “FA(3)”. This is the third version of Poland’s structured e-invoice schema, introduced for the mandatory phase (replacing the earlier FA(1) and FA(2) used in the pilot). The FA(3) schema is based on the EU’s EN 16931 standard data model (so it contains all core invoice information like seller, buyer, invoice date, line item details, tax amounts, etc.) but it is a Poland-specific extension that is not fully Peppol BIS 3.0 compliant. In practice, FA(3) includes additional fields required by Polish regulations (for example, specific identifiers like GTU codes for goods/services, or additional payment info) and some structural differences from the Peppol UBL schema. Nonetheless, it largely aligns with EU standards, which aids interoperability. Each e-invoice file will incorporate all the information currently on a paper invoice (e.g. seller/buyer legal details, sequential invoice number, dates, product/service description, net, VAT, gross amounts, currency, payment terms, etc.), encoded in XML elements. The Ministry of Finance released the FA(3) schema documentation (XSD) in May 2025 to software providers for integration. Businesses must ensure their ERP or billing systems can output invoice data according to this schema. Tools may be needed to map existing invoice fields into the FA(3) structure. [rtcsuite.com], [theinvoicinghub.com] [theinvoicinghub.com], [theinvoicinghub.com] [theinvoicinghub.com]
• KSeF as a Clearance Platform: KSeF operates on a clearance (continuous transaction control) model. This means an invoice must be **transmitted to the KSeF platform and validated by the system before it is considered legally issued. The supplier (issuer) sends the invoice data to KSeF, which checks it and assigns an official number, then makes it available to the buyer. In short, the tax authority’s system is an intermediary in delivery of every invoice (for in-scope transactions). This is similar to Italy’s SDI or Mexico’s CFDI systems.
  Invoice Clearance Process:
  1. Transmission: Invoices are sent to KSeF via a web service API. Companies will use either their own IT systems or an intermediary service to automatically transmit invoices in real-time (or in batches) to KSeF. The KSeF 2.0 API (for the FA(3) schema) is open for testing from 30 Sept 2025. Each company (or its software provider) must integrate with this API, which involves obtaining authentication credentials and following the API specifications for submission and retrieval. [kpmg.com], [rtcsuite.com]
  2. Authentication & Security: To ensure only authorized users send/receive invoices, KSeF uses a certificate-based authentication. Starting 1 Nov 2025, taxpayers can apply for a KSeF access certificate (digital certificate) for their systems. This certificate will be used in the API calls to authenticate the invoice sender. It replaces the earlier token method from the pilot, providing more secure, granular control. Certificates are valid 2 years and renewable. Alternatively, users (especially small businesses) can authenticate via the Polish e-ID (ePUAP) or Trusted Profile for manual portal use. Connections are encrypted, and each API call is logged. The system ensures non-repudiation – i.e., the sender is verified and cannot later deny the invoice’s issuance. [kpmg.com], [hlb-poland.global] [rtcsuite.com]
  3. Validation: When KSeF receives an invoice file, it performs automated validations. This includes schema validation (correct format, all required fields present, values in correct format) and content checks (e.g. verifying the seller’s and buyer’s NIP numbers are valid, dates are logical, arithmetic correctness of VAT calculations, etc.). If the invoice passes, KSeF assigns it a unique identifying number (KSeF number) and a timestamp. If it fails, KSeF returns an error message detailing the issue; the supplier must correct the invoice and resend. Only after passing validation does the invoice obtain a legal status of “issued”. The law specifies that the official date of issuance is the date provided by the supplier in the invoice (field P_1), not the moment of clearance – this is important for month-end invoices: e.g., an invoice dated 31 Jan but sent to KSeF on 1 Feb will count as issued on 31 Jan. KSeF will accept that as long as it’s within the allowed offline window (see below). This rule ensures compliance with VAT period reporting (the period of tax is based on invoice date rather than clearance date). [kpmg.com]
  4. KSeF ID and QR Code: Each cleared invoice is assigned a KSeF reference number (and possibly a hash or QR code). The invoice file in KSeF includes this unique ID. Starting in 2026, every invoice (electronic or printed copy) is expected to carry a QR code or link that allows verification in KSeF. For invoices delivered through KSeF, the buyer can see the invoice in their interface. But if an invoice is also sent externally (e.g. a PDF copy to a foreign customer or a paper printout given to a local customer for convenience), that copy must include the KSeF-issued QR code or a retrieval link. By scanning the QR or visiting the link, the recipient can confirm on the KSeF portal that the invoice is authentic and registered (and see basic details). This feature guards against fraud and ensures even invoices shared outside the system can be validated against the official record. It’s similar to Italy’s “QR Code” for e-invoices and gives peace of mind to buyers that the invoice is real (especially important for cross-border trades where the buyer doesn’t have direct KSeF access). The QR code is unified across online and offline invoices – if an invoice format (like an analog printout) can’t embed it as machine-readable, it can be provided as a separate attachment or printed image. [rtcsuite.com], [theinvoicinghub.com] [rtcsuite.com]
  5. Buyer Retrieval: Buyers access their invoices through KSeF using their own credentials or software integration. For a domestic buyer with a Polish VAT number, their accounting system can connect to KSeF (with appropriate authorization) to fetch incoming invoices, or they can download them via the KSeF web portal. By law, a buyer is deemed to have “received” the invoice when it is cleared and available in KSeF. This eliminates issues of postal delays or emails going astray – once in KSeF, the invoice is considered delivered. Businesses will likely set up automated polling to retrieve new invoices from KSeF into their accounts payable systems. Notably, even those not obligated to issue until April 2026 must be able to receive from February 2026, as mentioned. The KSeF portal allows assigning user roles – for example, a company can authorize its accounting firm to access its invoices, or an employee to download them. [rtcsuite.com], [theinvoicinghub.com]
  6. Acknowledgment & Archival: Upon successful processing, KSeF makes the invoice available to both parties and stores it securely. Poland’s regulations require keeping invoices for 5 years (or 10 years for some EU cross-border cases), and KSeF’s central archive fulfills this requirement. Taxpayers can retrieve past invoices from the system at any time, and auditors will have direct access to KSeF records (reducing the need for companies to supply physical archives during audits). In addition, companies may archive copies in their own systems for convenience, but the legal archive of record is KSeF’s database. [theinvoicinghub.com], [theinvoicinghub.com]
• System Interfaces: There are multiple ways to interact with KSeF:
  • Automated API Integration: Medium and large companies will integrate their ERP or invoicing software directly with KSeF’s REST API. After obtaining a certificate, their system will call endpoints to send invoices, check status, download invoices, etc. This allows high-volume processing. The Ministry opened API 2.0 testing in late Sept 2025 so that integrators can ensure smooth connectivity by the deadline. [kpmg.com], [rtcsuite.com]
  • KSeF Web Portal (Taxpayer Application): The government provides a free online app (accessible via browser and also a mobile app in development) for users to manually create and manage invoices. A test version of the new portal (adapted for FA(3)) is set to be released in Nov 2025. Through this portal, a user can log in with their National ID (or certificate) and manually input an invoice form which the system will convert to the XML and process. This is meant for small businesses or cases where integration isn’t feasible. The portal also allows viewing received invoices and downloading them (e.g. as PDF or XML) for record. [kpmg.com]
  • Mobile/Offline Tools: The Ministry has hinted at providing an offline invoicing tool (perhaps a desktop software or a mobile app) that can generate invoices in the required format without always being online. In any case, third-party accounting software providers are building user-friendly interfaces on top of the API, so businesses may use those as well.
• Authentication and Authorization: Each company can manage who has access to their KSeF account. They can grant permissions to employees or accountants to issue or read invoices on their behalf, through KSeF’s admin console. Also, foreign entities with a Polish tax registration will be given methods to obtain a login (likely via a trusted intermediary or a designated electronic ID, since ePUAP is mainly for Polish citizens). Ensuring that the right people/systems are authorized is critical: unauthorized issuance of an invoice in KSeF could have real tax implications, so security is tight. The introduction of invoice-issuer certificates adds an extra layer – companies will likely install these digital certificates on their servers or cloud applications to sign API requests. [rtcsuite.com]
• Offline Mode (“Offline24”): The law recognizes that sometimes a taxpayer might be unable to connect to KSeF in the moment (due to technical issues, internet outage, or system downtime). To address this, an “offline mode” is provided:
  • A taxpayer can issue an invoice outside of KSeF and later upload it. The rule is that if KSeF is unavailable or the issuer cannot connect, they may still create the structured invoice and give it to the buyer (or at least commit the transaction), then transmit it to KSeF within 24 hours (by end of the next business day). This is often called the “offline24” rule. The new amendment makes offline mode a permanent feature (not just for specific industries). For example, if a sale occurs on Saturday when perhaps the system is down for maintenance, the seller could issue a provisional invoice (likely using the same FA(3) format stored locally) and upload it to KSeF on Monday. The invoice’s issue date (in content) remains the Saturday date, and KSeF will accept that if uploaded in time. The law clarifies that the “issue date” is whatever date the taxpayer put on the e-invoice (field P_1), so in offline mode, the invoice can still carry the original sale date. Once uploaded, KSeF processes it and assigns a number; the invoice is then official. The buyer can verify later that it was reported. [kpmg.com], [rtcsuite.com] [rtcsuite.com] [kpmg.com]
  • Offline mode is also useful for businesses operating in areas with unreliable internet, or for mobile sales (e.g. deliveries) where real-time connection may be impractical. It gives operational flexibility while still requiring timely reporting.
  • The regulations specify which situations justify offline issuance (likely system downtime, maybe the taxpayer’s systems issues, etc.) and that the invoice must be sent as soon as the problem is resolved, no later than the next working day. Misuse of offline mode (e.g. routinely delaying submission without cause) could be subject to penalties after 2026, but during the grace period no fines apply. The buyer receives the invoice when it’s eventually in KSeF; if they got a copy earlier, they should verify it later via QR code. Overall, offline24 ensures business continuity – invoicing can continue even if KSeF momentarily cannot be reached. [hlb-poland.global]
• Attachments: A new feature in KSeF (from 2026) is the ability to add attachments to an invoice. Under the current voluntary system, invoices could not include separate annexes. With the law change, a supplier can attach additional documents (e.g. detailed price lists, specifications, or large appendices that don’t fit into invoice fields) to the e-invoice. The taxpayer must notify the tax authority by 1 January 2026 of their intention to use attachments, likely so KAS can enable that feature for them. Attachments are considered an integral part of the invoice, which is helpful for sectors that need to provide complex supporting data (e.g. construction projects, long list of serial numbers, etc.). There may be some limits on file types or size, and these attachments would be stored in KSeF alongside the invoice XML. This enhances the system’s usability, bringing it closer to what businesses do in practice (often sending PDF attachments with invoice data). If attachments are used, it’s likely the invoice still must be interpretable on its own for VAT purposes; the attachment is supplementary. [kpmg.com], [hlb-poland.global] [kpmg.com] [hlb-poland.global]
• Integration with Peppol: Poland’s KSeF system is expected to interoperate with the Peppol network for cross-border and B2G contexts. The invoicinghub info indicates KSeF is connected to Peppol as well. This suggests that a foreign company could send a Peppol BIS 3.0 invoice which might be routed into KSeF, or vice versa. As of 2025, PEF (the separate platform) handles Peppol invoices for B2G, and KSeF handles FA(3). The government may maintain both channels for a time: suppliers to Polish public bodies can choose to use the EU-standard Peppol BIS via PEF, or send via KSeF (FA(3)). In the long run, PEF and KSeF should converge, possibly with KSeF becoming the single window (and maybe accepting Peppol BIS format by converting it internally). For now, businesses (especially multinational ones) should note that KSeF’s FA(3) is not 100% EN16931 compliant, which means direct cross-platform compatibility might require mappings. However, Poland aims to align with EU standards where possible. This dual system mostly affects B2G and cross-border – for purely domestic trade, everyone will simply use KSeF’s native format. [theinvoicinghub.com], [theinvoicinghub.com] [theinvoicinghub.com]

Implementation Timeline & Transition Period

• During the first two months of mandatory operation (Feb–Mar 2026), mid-size and small firms not yet required to use KSeF can still issue invoices via old methods to avoid disrupting commerce with trading partners who haven’t fully switched. This means some PDF invoices might still circulate until April 1, 2026 if both parties are not large. [hlb-poland.global]
• Penalty holiday: No fines for failing to use KSeF or for errors (like delayed submissions) will be levied until January 2027. Originally, Polish law envisioned fines of up to 100% of VAT or up to PLN 18,750 for non-compliance, but these are suspended for 2026 to emphasize education over punishment. [kpmg.com]
• Continued use of cash registers: Through 2026, businesses can still issue invoices via cash register printers (which print simplified invoices) without immediately integrating each receipt into KSeF. However, by 2027, even those will likely have to be reported (the law foresees integration of cash register systems with KSeF or use of a special procedure for B2C). [kpmg.com]
• Optional early adoption: Businesses not in the first phase can voluntarily start using KSeF before their deadline. For example, a medium-sized company can opt to switch on KSeF in February 2026 even though legally required only by April – this might be done if their systems are ready and they want to unify processes early. The transitional rules allow such companies to still issue conventional invoices in a pinch until April if something goes wrong, providing flexibility.

Impact on Domestic vs Cross-Border Transactions

• Domestic B2B Transactions: For business-to-business transactions within Poland, KSeF will become the sole channel for invoicing. This means that for a Polish buyer, receiving an invoice will increasingly mean logging into KSeF or using integrated software to fetch it rather than checking the mail or email. As a result, domestic buyers can only deduct VAT on purchases if the invoice is in KSeF (after the mandate). If a supplier fails to put an invoice through KSeF when required, that invoice technically isn’t valid for VAT purposes. Tax authorities could deny the input VAT deduction to the buyer in such a case. (The exact enforcement of this will likely tighten after the grace period; in 2026 they may be lenient, but by 2027, “no KSeF, no VAT deduction” will effectively be the rule). For suppliers, this centralizes compliance: once you upload to KSeF, you don’t need to send the invoice through other means to a domestic customer – the system handles delivery. It may also simplify domestic invoice reconciliation processes: since both sides have access to the same invoice data on KSeF, disputes over whether an invoice was sent or received should diminish.
• Business-to-Government (Public Procurement): Public sector invoicing in Poland will undergo a shift from the PEF platform (which uses EU standardized format) to KSeF. Currently, as noted, public entities accept e-invoices via PEF/Peppol and also still accept paper/PDF in many cases. With KSeF, government agencies will be able to receive supplier invoices directly from KSeF. Since they are VAT-registered entities with NIP numbers, they will appear in the system like any buyer. Government departments will need to adapt their accounts payable processes to retrieve invoices from KSeF or possibly get them via a Peppol integration with KSeF (as KSeF is Peppol-connected). The law also extends the list of entities that can be issued invoices outside KSeF to include entities without identification numbers – this covers individuals, but also possibly some specific public bodies that might not have a NIP (though most do). Essentially, B2G suppliers must use KSeF by 2026, ensuring the government gets structured data. For foreign suppliers to Polish government, Poland will likely accept a Peppol invoice which then enters KSeF, or they may be given a way to use KSeF directly. This increases interoperability and could streamline public procurement payments (the government will have an easier time verifying and paying invoices with consistent data). It also means the Polish government will eventually phase out the older PEF platform in favor of KSeF, unifying B2B and B2G under one umbrella system. [theinvoicinghub.com], [theinvoicinghub.com] [kpmg.com]
• Cross-Border B2B Transactions (Exports & Imports):
  • Outgoing (Polish supplier to foreign customer): If a Polish company sells to an EU or non-EU business, it must issue the invoice via KSeF just like a domestic invoice. The invoice will likely be marked as “NP” (not subject) or “0% VAT” if it’s an intra-Community supply or export, but it still goes into the system for reporting. However, the foreign customer typically will not have direct access to KSeF (since only entities with a Polish system login can retrieve invoices). Recognizing this, Polish regulations allow the supplier to send the invoice to the foreign buyer through other channels (email, EDI, etc.) outside KSeF. Crucially, that externally-sent invoice copy must have the QR code or link for the buyer to verify it in KSeF. For example, a German customer receives a PDF of the invoice with a QR code; by scanning it, they can see on the Polish KSeF portal (likely an English interface or a verification page) that the invoice is registered and valid. This ensures trust and also helps the Polish supplier prove to tax authorities that they reported the sale. In effect, KSeF acts as an e-reporting tool for exports – replacing the need for separate listings of issued zero-VAT invoices (in the future, it might eliminate the EC Sales List if EU-wide reporting becomes real-time). From the foreign buyer’s perspective, not much changes except the invoice format might look different (with QR code and structured layout). But they don’t need to do anything special – the Polish supplier takes care of KSeF compliance. [theinvoicinghub.com] [rtcsuite.com], [rtcsuite.com] [rtcsuite.com], [theinvoicinghub.com]
  • Incoming (foreign supplier to Polish buyer): If a foreign company (without a Polish VAT number) issues an invoice to a Polish business, that invoice will not pass through KSeF, because KSeF is only for invoices issued by Polish-registered taxpayers. The Polish buyer will receive that invoice through traditional means (email, etc.) and will continue to handle VAT on it via reverse charge or import VAT as appropriate. There is no obligation or mechanism for a Polish buyer to “upload” invoices from foreign suppliers into KSeF. One exception, as mentioned, is self-billing: if the Polish buyer is the one issuing the invoice (self-billing) on behalf of a foreign supplier who has no Polish NIP, the invoice can be handled outside KSeF (because KSeF won’t accept an issuer with no PL ID). In summary, pure cross-border incoming invoices remain outside KSeF’s scope – at least until possibly some future EU system links them. Polish companies will thus maintain a process for regular AP handling of foreign invoices. However, Poland may still require reporting of those in the SAF-T or future digital reports. (Currently, Polish companies report foreign purchase invoices in the JPK_VAT file; once KSeF is live, domestic purchase invoices will not need manual reporting, but foreign ones might still be reported until an EU solution arrives.) [rtcsuite.com]
  • Foreign companies with a Polish VAT registration: If a foreign business is registered in Poland for VAT (e.g. via a fixed establishment or direct registration), and is issuing invoices under their Polish VAT number, those invoices are subject to KSeF. The HLB article noted that the obligation extends to foreign companies with a fixed establishment in Poland. This means a company from, say, the US that’s VAT-registered in Poland to sell locally must comply like any Polish company. The ambiguity of what constitutes a fixed establishment could raise questions, but as a rule, if you have a PL NIP and issue Polish VAT invoices, you must use KSeF for those. Foreign firms in this situation will need to obtain KSeF certificates and integrate or use an intermediary service to issue their invoices via KSeF. This levels the playing field – all entities in Poland’s VAT system adhere to the same process. [hlb-poland.global]
• VAT Compliance and Reporting: Real-time e-invoicing will significantly strengthen VAT compliance:
  • The Polish tax administration (KAS) will have instant access to all B2B invoice data – enabling them to cross-check sellers’ output VAT and buyers’ input VAT claims continuously. This should help detect fraud (like missing trader or fake invoices) much faster. It may reduce Poland’s VAT gap and is one reason Poland pursued KSeF early.
  • No more duplicate reporting: Currently, businesses list invoices in the monthly JPK_V7M (VAT return + SAF-T) report. With KSeF, the authorities already have the transaction data, so these reports might be simplified to just summary info. While initially companies might still file VAT returns, over time Poland could move to pre-filled returns or even eliminate the need for separate VAT listings, as Italy has done post e-invoicing. Already, the requirement for an annual sales listing (VAT-27) was removed in Italy once e-invoicing gave tax authorities all invoice data. Poland may follow suit, possibly scrapping the domestic part of the SAF-T. The KSeF Act doesn’t yet explicitly remove JPK obligations, but we expect guidance on this as the system stabilizes.
  • Audit and control: Tax audits will become more data-driven. Auditors can query KSeF for any taxpayer’s invoices filtered by date, amount, counterpart, etc. This reduces the burden of companies to produce documents in audits—since the invoices are in the tax system’s possession. It also means businesses must be extra diligent: any invoice (and its corrections) you issue is immediately visible to the tax office, leaving little room for “repairing” mistakes quietly. Companies should implement stronger pre-validation on their side to ensure invoice data is correct before sending to KSeF (to avoid rejections or incorrect info reaching the tax authority).
  • Cross-border transparency: While KSeF mainly captures domestic transactions, it also captures exports and certain imports (like reverse-charged services where a Polish supplier issues a self-invoice). This gives the Polish tax authority better information on cross-border flows. For intra-EU sales, KSeF data could eventually replace the need for EC Sales List declarations if the EU changes the law by 2028. Even before that, Poland will have detailed data on exports which can be matched with customs/export records to validate zero-rating claims.
  • Purchaser self-identification: The Act introduces an obligation for buyers to provide their tax ID to suppliers for invoicing purposes. Essentially, if a purchase is for business purposes, the buyer should ensure the supplier has their NIP (even if the buyer is VAT-exempt or not VAT-registered, their tax ID is used). This is to ensure that the invoice in KSeF correctly tags the buyer. It’s now in the buyer’s interest to do so, because if they fail, the invoice might be issued treating them as a non-business consumer in KSeF, which could complicate VAT deduction. So businesses will need to communicate their VAT/NIP number clearly in all procurement processes. [kpmg.com]
• International Interoperability: Since KSeF is a national system, invoices between Polish companies are fully handled inside it. For invoices between a Polish and a foreign company, there’s an interoperability challenge – one side is in KSeF, the other is not. Poland’s solution is pragmatic: require the Polish side to use KSeF (so the tax is happy) but allow parallel use of standard formats (PDF or Peppol) to actually deliver the invoice to the foreign party. The inclusion of a QR verification code means any recipient worldwide can validate the invoice’s authenticity via the internet without needing special credentials. This actually might increase trust from foreign customers: they can confirm that an invoice claiming zero VAT was indeed reported to Polish authorities, which adds credibility. Similarly, if a Polish company receives a questionable invoice from abroad, they can check if that foreign supplier perhaps had a Polish NIP and should have used KSeF. [rtcsuite.com], [rtcsuite.com] [theinvoicinghub.com]

Implications for VAT Compliance and ERP Integration

• Software Adjustments: Enterprises must update their billing systems (ERP, accounting software, invoicing tools) to support the FA(3) XML format and KSeF connectivity. Many major ERP vendors (SAP, Oracle, Microsoft Dynamics, etc.) are providing KSeF integration patches or add-on modules. For example, SAP has released notes for Poland e-invoicing that map SAP invoice fields to the required FA(3) fields and handle the API calls. Some businesses may use third-party e-invoicing middleware or service providers (like Basware, Sovos, Pagero, etc.) which act as a bridge: the ERP sends invoice data to the provider, and the provider transforms and submits it to KSeF. In either case, a mapping exercise is needed to ensure every data point on an invoice (tax codes, invoice lines, addresses, etc.) is correctly populated in the KSeF XML. This might reveal data gaps; e.g., companies have to record the Code of the fiscal cash register or an internal system ID because KSeF schema might require it for certain invoices. Starting early with this mapping is crucial, and many companies began in 2025 when the schema was published.
• System Certification and Testing: After updating software, companies should use the test environment (open from Sept 2025) to do end-to-end testing. They should simulate various scenarios: domestic sale, export sale, credit note, invoice with attachment, offline scenario, etc. This will help catch issues like invalid data or connectivity problems. The testing phase also includes securing the KSeF certificate for production and installing it properly on their servers. Many companies will run tests in late 2025 to ensure that come Feb 2026, sending an invoice to KSeF is as routine as printing it used to be. KPMG noted open API testing and certificate availability timelines that companies must align to. [kpmg.com], [kpmg.com]
• Master Data Preparation: Accurate master data (customer info, product info) becomes even more important. For instance, buyer identification: the KSeF invoice requires the buyer’s correct name and address and NIP. Companies need to ensure their customer master records have the NIP (or tax ID) for each business customer. If not, they must obtain it. Similarly, if a foreign customer doesn’t have a Polish NIP, the system should mark them appropriately so the invoice is flagged for external sending. Fields like unit of measure codes, country codes, currency codes, payment account numbers, etc., all need to be standardized according to the KSeF format. Cleaning up and enriching master data in 2025 is a key task to avoid KSeF validation errors in 2026.
• Internal Invoice Numbering vs. KSeF Number: Companies typically have internal invoice numbers. Under KSeF, they will still assign an internal sequence number that goes in the invoice (field “invoice number” P_2). KSeF does not override this; instead, it adds a separate KSeF reference. The law clarified that the invoice number visible to buyer remains the one the supplier assigned (the KSeF ID is an addition, not a replacement). So businesses should continue their numbering practices, ensuring uniqueness as before. They may need to decide how to store the KSeF ID – typically, their ERP will have an extra field to save the KSeF confirmation number and maybe the timestamp and QR code. This integration of KSeF info back into ERP is important for audit trail. For example, if a customer later queries an invoice, the company can look up both its internal number and see the KSeF ID to quickly verify it was accepted. [kpmg.com], [theinvoicinghub.com]
• Receiving and Processing Purchase Invoices: ERP/AP systems must also adapt to retrieve incoming invoices from KSeF. Businesses could use an inbound API mechanism or periodic downloads. Some AP software may directly connect to KSeF to pull invoices into a workflow. Others might rely on email notifications plus logging into the portal. Large companies will opt for integration to automate matching of purchase orders to e-invoices and posting to the ledger. This might involve new middleware or updates to existing OCR/EDI solutions (though with structured data, OCR is no longer needed for those invoices). Companies should treat this as part of integration testing – ensuring they can capture incoming e-invoices and that they contain all data needed for booking (e.g. PO number references, etc.). The mention that “mandatory receipt of KSeF e-invoices starts for everyone on 1 Feb 2026” underscores that even those not sending e-invoices then must have a way to get them. [rtcsuite.com]

• Invoice Approval and Issuance: Internally, the process of issuing an invoice will change. Instead of printing or emailing upon approval, staff will now possibly trigger a “Send to KSeF” action. Businesses should define at what point an invoice is considered “issued” – likely once KSeF returns a success message. They might implement a status in the ERP: e.g., Pending KSeF, KSeF Accepted, KSeF Rejected. Accounting policies must be adjusted so that revenue is only recognized if the invoice is successfully cleared (since a rejection means no valid invoice yet). The law’s allowance that the content date is the issuance date helps alignment, but businesses might need to set cut-offs to ensure they upload invoices within required timeframes (especially at month-end).
• Handling Errors: Companies must establish procedures for handling invoice rejections or adjustments. If KSeF rejects an invoice (say due to a formatting error or invalid data), who in the team monitors those errors and fixes them? Likely, accounting or IT will need a monitoring system or dashboard for KSeF submissions. Some errors might require correcting master data or contacting the customer for correct info (for example, if a buyer’s NIP was wrong and KSeF rejects it). Quick turnaround on these is needed to avoid delays in invoicing and cash flow.
• Credit Notes/Cancellations: Polish VAT law already had a notion that you cannot simply cancel an issued invoice; you must issue a corrective invoice (credit note or debit note). With KSeF, this remains – if an invoice is wrong and already cleared, you cannot delete it; you must issue a structured correction through KSeF referencing the original. The new system simplifies some correction rules (the law mentions simplified settlement of corrections in KSeF). Finance teams will need to follow the updated correction workflow – likely entering the correction in the ERP, sending it to KSeF, and ensuring the buyer receives/applies it. KSeF links corrections to original invoices, which helps maintain clarity. [kpmg.com]
• Consumer Invoices and Receipts: For companies dealing with both B2B and B2C, they may maintain dual processes: KSeF for B2B, cash register or other methods for B2C. The law clarifies consumer invoice rules, likely allowing them in KSeF if the consumer provides info. Companies might decide whether to optionally use KSeF for certain B2C scenarios (e.g., high-value consumer sales where they want the invoice centrally stored). Policies should be set for when a consumer sale triggers a KSeF invoice vs just a receipt. [kpmg.com]
• Accounts Payable Verification: AP departments should update their VAT deduction process: before booking a purchase invoice’s VAT, they may be required (by internal control or by auditors) to verify that the invoice exists in KSeF (for domestic purchases). This could be as simple as ensuring they’ve downloaded it from KSeF with a valid ID or scanning the QR on a paper copy. This is a new step akin to verifying e-signatures previously. It ensures that if a supplier somehow tries to send a paper invoice when they should use KSeF, the buyer can catch it and insist on a KSeF version (because without it, the input VAT is risky). The HLB piece pointed out uncertainty on whether invoices outside KSeF give right to deduct VAT – the safe assumption is no, once mandatory. So AP teams become gatekeepers: if a vendor (who by the date should use KSeF) sends a PDF invoice, AP should push back and request a proper KSeF invoice. [hlb-poland.global], [hlb-poland.global]

• Staff Training: Accountants, billing specialists, and IT support all need training on the KSeF system. They should learn how to use the KSeF portal (for troubleshooting or manual tasks), how to interpret error codes, and how the new process differs from the old. For example, invoice issuance may become faster (no postal mailing) but requires understanding of the KSeF statuses. Teams should also be trained on the offline procedures: when is it okay to issue offline, how to later send, how to mark those invoices.
• Vendor/Customer Communication: Companies will also need to inform their counterparties about the change. By early 2026, many Polish companies will be aware, but it’s good practice to notify domestic clients that “we will send invoices via KSeF starting Feb 1 – please retrieve them accordingly” and possibly provide instructions or agree on sending a courtesy copy by email if the client prefers. For foreign customers, a friendly note explaining “Poland’s new e-invoice system” and that their invoice will include a QR code for verification might reduce confusion. Similarly, companies should inform foreign suppliers (with PL VAT) that if they are issuing on their behalf (self-billing) or expecting invoices involving Poland, things have changed. Good communication ensures everyone knows what to expect, minimizing disputes or payment delays.
• Cooperation with IT/Consultants: Many businesses are engaging consultants or their software vendors to assist in the KSeF roll-out. Given that 10,000+ stakeholders were consulted by the Ministry during planning, there is a significant community of practice emerging. Businesses should leverage external expertise – e.g., attend webinars by the tax administration, reference guides (like the PwC or KPMG alerts), and share experiences within industry groups. Particularly for multinational groups, the Poland team might coordinate with colleagues in Italy or France (who have similar systems) to adopt best practices in integration and compliance controls. [dynatos.com]

• Efficiency Gains: No more printing or mailing invoices, faster delivery to customers, automatic validation catching errors early, and potential automation of invoice processing and accounting. Over time, less effort on VAT reporting (since the system captures data).
• Reduction of Fraud and Errors: It will be very difficult for fraudulent invoices to circulate, as each must be cleared by KSeF with valid seller/buyer IDs. For businesses, this means less risk of unknowingly accepting fake invoices. It also means your own errors (e.g., forgetting to invoice something) will be reduced, as everything is systematized.
• Cash Flow Management: E-invoices reach customers instantly, which can lead to faster payment cycles. Also, with all invoices tracked, companies might have better insights into their receivables and payables in real-time.
• Audit Simplification: Tax audits or inquiries should be simpler – instead of scrambling to find documents, companies can rely on KSeF records. The tax office might even do desk audits using KSeF data without coming on-site.

• Initial Investment: Upgrading or changing the invoicing system has costs – software licenses, development, testing, possibly new hardware (for certificates, etc.), and training. The government’s phased approach and the grace period mitigate some risk, but the investment is front-loaded in 2025.
• Change Management: Employees must adapt to new tools, which may temporarily slow down invoicing processes if there’s a learning curve. Companies should allocate time and resources for this.
• Reliance on System Uptime: When KSeF is mandatory, any outage in the system or connectivity issues could delay invoicing. The offline24 mode provides relief, but if outages were prolonged, it could create backlogs. The audit in 2023 found flaws that are presumably being fixed, but businesses will want to have contingency plans (e.g., ensure they save a local copy of any invoice generated during an outage to upload later). [dynatos.com]
• Complex Cases: Certain industries (e.g. insurance, finance, travel agencies under margin scheme) have special VAT invoicing rules. Ensuring KSeF accommodates those (or learning how to adapt them to KSeF) is an additional task. The law covers most, but companies in those sectors should verify how to implement (for example, invoices with split payment not needing KSeF number until 2027, or second-hand goods schemes – are they supported in schema? likely via special codes). [kpmg.com]
• Working with Partners Not Ready: In early 2026, some suppliers or customers might lag in readiness. While large companies will generally be ready (since they’re forced first), some mid-sized might drag feet until April. This could cause some temporary confusion (e.g., a large company sends an e-invoice that a smaller customer doesn’t check in KSeF). Businesses may need to actively reach out to partners to encourage them to get on board or otherwise make interim arrangements (like also emailing a PDF copy for a couple months if requested, even though legally the invoice of record is in KSeF).
• International Coordination: Multinationals might need to adjust their group policies. For instance, some companies centralize their AR in a shared service center abroad; if that center now needs to interface with KSeF, it must have the means (maybe via a local proxy). Ensuring global finance teams understand Poland-specific rules is important.

• Timely VAT Payments: The tax authorities will easily spot late issuance of invoices (since they expect, say, invoices dated March to be uploaded by early April at worst). This could pressure businesses to issue invoices on time or face inquiries. It also means VAT on sales will be accounted for in the correct period more consistently. Conversely, VAT deductions will be more transparent – tax authorities can match a purchase invoice in buyer’s data with the sale invoice in seller’s data in KSeF automatically, flagging discrepancies immediately.
• Reducing VAT Fraud: KSeF is expected to reduce fraud like fake invoice schemes, because an invoice without a real supplier behind it cannot enter the system. This levels the playing field for honest businesses and ultimately can lead to a fairer market.

Key resources

• Polish Government: Questions and answers – KSeF
• The National System of e-Invoices
• National e-Invoice System (KSeF)
• Website European Commission – eInvoicing in Poland

• See also
  • E-Invoicing/Real Time Reporting – What can you find on VATupdate.com
  • Worldwide Upcoming E-Invoicing mandates, implementations and changes – Chronological
  • Collection of E-Invoicing Guides – Worldwide – VATupdate
  • Briefing / Comprehensive Guides (incl. podcasts)

• Join the Linkedin Group on Global E-Invoicing/E-Reporting/SAF-T Developments, click HERE