Poland KSeF E-Invoicing Requirements: Complete 2026 Guide

KSeF (Krajowy System e-Faktur) is Poland's mandatory national e-invoicing platform. Large taxpayers have been required to issue invoices through KSeF since February 1, 2026, all remaining VAT-registered businesses must comply by April 1, 2026, and micro-entrepreneurs follow from January 1, 2027. Every business must be capable of receiving KSeF invoices as of February 1, 2026, regardless of its own sending deadline.

After four postponements dating back to 2024, KSeF 2.0 launched on schedule on February 1, 2026. The system is now live and operational, removing any remaining uncertainty about whether Poland would delay again. The mandate is irreversible.

Most guides to Poland's e-invoicing requirements focus narrowly on the sender's compliance obligations: how to generate structured XML, authenticate with the platform, and meet filing deadlines. This guide takes a different approach. Beyond covering the regulatory and technical requirements in full, it addresses the practical operational impact on AP workflows and invoice receivers. If your team processes inbound invoices from Polish suppliers, or if your organization operates in Poland and needs to handle the coexistence of KSeF XML invoices alongside legacy PDFs and foreign supplier documents, the receiver-side perspective covered here is essential.

This guide covers the regulatory requirements, technical specifications, and practical operational impact across all three compliance phases, from KSeF's origins and confirmed timeline through FA(3) XML schema requirements, offline contingency modes, penalties, and a readiness checklist built around the AP perspective.

What Is KSeF and Why Poland Is Mandating E-Invoicing

KSeF (Krajowy System e-Faktur) is Poland's centralized national e-invoicing system, operated by the Polish Ministry of Finance. It functions as a clearance model: every qualifying invoice must be issued through the KSeF platform, which validates the document against the required XML schema, stores it in a central repository, and distributes it to the recipient. No invoice is considered legally issued until KSeF has processed and accepted it.

The path to a live system was anything but smooth. Poland originally scheduled the KSeF mandate for January 1, 2024, then pushed it to July 2024. In January 2024, the Finance Minister suspended the rollout indefinitely, citing major system errors uncovered during testing. The Sejm passed a revised Act in May 2024 establishing a new timeline, and the President signed the final legislation into law on August 27, 2025. KSeF 2.0 launched on February 1, 2026 as planned, marking the definitive start of Poland's national e-invoicing system.

The driving force behind the mandate is fiscal. Poland's VAT compliance gap has been a persistent drain on public revenue. According to the European Commission's VAT Gap Report 2025, Poland's VAT compliance gap reached an estimated EUR 10.5 billion in 2023, equivalent to 16.0% of total VAT liability and significantly above the EU average of 9.5%. KSeF is designed to close this gap through real-time invoice validation and a centralized digital audit trail that gives tax authorities immediate visibility into B2B transactions.

Poland's e-invoicing mandate does not exist in isolation. It is part of a broader EU-wide shift toward mandatory structured electronic invoicing, aligned with the EU ViDA (VAT in the Digital Age) directive. For businesses operating across multiple European markets, Poland joins Italy, France, and Germany in requiring compliant e-invoicing infrastructure. If your organization trades across borders, understanding how these national mandates intersect is critical. A global overview of e-invoicing mandates provides broader context on the regulatory trajectory across major economies.

With the system now live and processing invoices, the confirmed compliance deadlines determine what your business needs to do and by when.

KSeF Mandatory Dates: The Confirmed 2026-2027 Timeline

Poland's KSeF rollout follows a three-phase schedule based on business size, with the first phase already live. The table below captures the exact dates, affected entities, and what each phase requires.

Phase	Date	Who Must Comply	What Changes
Phase 1	February 1, 2026	Large taxpayers with annual turnover exceeding PLN 200 million (~EUR 46 million)	Must issue all B2B invoices through KSeF
Phase 2	April 1, 2026	All remaining VAT-registered businesses	Must issue all B2B invoices through KSeF
Phase 3	January 1, 2027	Micro-entrepreneurs with monthly sales of PLN 10,000 or less	Must issue through KSeF; financial penalties for KSeF-specific violations also begin

Phase 1 launched on schedule, meaning large enterprises are already operating within the system. Phase 2 follows just two months later, leaving a narrow window for mid-sized and smaller VAT-registered businesses to finalize their technical setup.

The Receiving Obligation Most Businesses Are Missing

Here is the detail that catches many finance teams off guard: every business must be able to receive KSeF invoices from February 1, 2026, regardless of when their own sending deadline falls. A company in the Phase 2 or Phase 3 category still needs receiving infrastructure operational right now, because their large-enterprise suppliers are already issuing through KSeF. If your AP department cannot pull and process structured invoices from the KSeF platform today, you are already behind.

Grace Period and Penalty Structure

Throughout 2026, the Polish Ministry of Finance has established a grace period with no financial penalties for KSeF-specific violations. This buffer gives businesses room to resolve technical integration issues, correct XML formatting errors, and adapt internal workflows without immediate fines. However, this grace period applies only to KSeF-specific rules. Standard VAT sanctions, including penalties for late or incorrect invoicing under existing tax law, remain fully in effect from February 1, 2026. The distinction matters: getting your KSeF transmission wrong may be forgiven temporarily, but failing to meet underlying VAT obligations will not.

Starting January 1, 2027, the grace period ends and dedicated KSeF penalties take effect alongside the micro-entrepreneur mandate.

Poland Within the Broader EU Shift

Poland is not implementing e-invoicing in isolation. France's parallel e-invoicing mandate follows a similar phased rollout beginning in 2026, and several other EU member states have announced their own timelines. This coordinated push toward structured e-invoicing as the foundation for real-time tax reporting across the bloc means businesses operating across European borders should treat Poland KSeF e-invoicing requirements as one piece of a larger compliance picture that will only expand.

With the timeline confirmed, the next consideration is scope.

Which Businesses and Invoices Fall Under KSeF

Determining whether KSeF applies to your organization requires examining two variables: the type of entity issuing the invoice and the category of transaction. The mandate is broad, but it is not universal, and the distinction between in-scope and out-of-scope invoices matters for how you design your compliance approach.

Invoices That Must Go Through KSeF

The following invoice types fall within the mandatory KSeF scope:

Domestic B2B transactions: any invoice issued between two Polish-registered businesses for goods or services supplied within Poland.
B2G (business-to-government) transactions: invoices issued to public sector entities, which were among the earliest use cases for structured e-invoicing in Poland.
Exports and intra-Community supplies at the 0% VAT rate: Polish sellers must submit these invoices to KSeF even when the buyer is located outside Poland. The zero-rate designation does not exempt the transaction from the platform.
Corrective invoices (faktury korygujące): corrections to previously issued invoices must also be submitted through KSeF, linked to the original invoice's KSeF reference number.
Self-billing invoices: where the buyer issues the invoice on behalf of the seller under a self-billing arrangement, those invoices are also in scope.

Invoices That Are Out of Scope

Not every document needs to pass through KSeF. The following are excluded from the mandate:

B2C invoices: invoices issued to individual consumers are not required to go through KSeF, though businesses may voluntarily submit them.
Inbound cross-border invoices from non-Polish suppliers: if a foreign company without a Polish fixed establishment sends you an invoice, that document will not appear in KSeF.
Proforma invoices: these are not considered VAT invoices under Polish law and fall outside KSeF entirely.
Internal invoices: documents used for internal accounting purposes are excluded.
Invoices under OSS/IOSS schemes: transactions reported through the One-Stop Shop or Import One-Stop Shop mechanisms are not processed through KSeF.

Rules for Foreign Companies and Poland E-Invoicing

The treatment of foreign companies under KSeF is one of the most frequently misunderstood aspects of the mandate. The core rule is straightforward, but the details require attention.

Foreign companies are exempt from KSeF unless they maintain a Polish fixed establishment (stałe miejsce prowadzenia działalności) that is directly involved in the supply. A fixed establishment in this context means a permanent business presence with sufficient human and technical resources to carry out transactions, not merely a warehouse or a mailing address.

Critically, holding a Polish VAT registration alone does not trigger KSeF obligations. A foreign company that registers for Polish VAT to handle reverse-charge transactions or intra-Community acquisitions is not required to issue invoices through KSeF, provided it lacks a qualifying fixed establishment.

On the issuing side, Polish sellers must submit invoices to KSeF for zero-rated exports and intra-EU supplies. When a Polish business invoices a foreign buyer, the seller submits the structured invoice to KSeF as required, but must also provide the buyer with a separate copy of the invoice, typically as a PDF or other agreed format, since foreign buyers without a Polish fixed establishment do not have access to the KSeF platform.

What This Means If You Receive Invoices

From the accounts payable perspective, the scope rules create a practical challenge worth planning for now. Even if your business is not required to issue invoices through KSeF until its applicable sending deadline, you may already be required to receive structured invoices from suppliers who fall under an earlier mandate phase.

If your organization works with both domestic and foreign suppliers, you will handle a mixed intake: some invoices arriving as structured XML through KSeF, others arriving as PDFs, scans, or other traditional formats from foreign suppliers whose invoices never touch the Polish system. Building a receivables workflow that accommodates both channels from the start prevents the need to retrofit your process later.

For every invoice that does pass through KSeF, it must conform to the FA(3) XML schema.

FA(3) XML Schema: Technical Requirements for KSeF Invoices

KSeF accepts invoices in one format only: FA(3) XML. PDFs, scanned images, Word documents, and any other unstructured file types are not valid KSeF invoices and will be rejected by the platform. For businesses that have spent years issuing and receiving PDF invoices via email, this represents a fundamental shift in how invoice data must be structured, transmitted, and stored.

Understanding the FA(3) Schema Structure

FA(3) is the third iteration of Poland's structured invoice schema, built on the European standard EN 16931 and aligned with Peppol BIS Billing 3.0. The schema contains over 300 data fields, though not all are required for every invoice. Some fields are universally mandatory, while others become required based on the transaction type, VAT treatment, or parties involved.

The schema is organized into mandatory and optional structural elements:

Mandatory elements:

Naglowek (Header): invoice metadata including schema version, currency, and submission details
Podmiot1 (Seller): full identification and tax data for the invoice issuer
Podmiot2 (Buyer): full identification and tax data for the invoice recipient
Fa (Invoice Data): line items, amounts, VAT rates, and calculation totals

Optional elements:

Podmiot3 (Third Party): used when a third party issues an invoice on behalf of the seller
Stopka (Footer): additional annotations or supplementary information
Zalacznik (Attachment): supporting documentation linked to the invoice

The distinction between mandatory and context-dependent fields matters for implementation planning. A standard domestic B2B invoice may require 40-60 fields, while a multi-currency transaction with split VAT treatment and third-party issuance could require significantly more. Finance teams should work with their ERP vendors or integration partners to map existing invoice data against the full FA(3) field set and identify gaps. Since the FA(3) schema builds on the mandatory fields defined under Poland's VAT invoice regulations, understanding which elements Article 106e requires for each of the ten invoice types is a practical starting point for that mapping exercise.

Authentication Methods for KSeF Access

Accessing the KSeF platform, whether to submit invoices, retrieve them, or manage permissions, requires authentication through one of four supported methods:

Qualified electronic seal or qualified electronic signature: the most secure option, using EU eIDAS-compliant certificates. Suited to organizations that already hold qualified certificates for other regulatory purposes.
Trusted Profile (Profil Zaufany): Poland's national digital identity system, widely used for interacting with government platforms. Many Polish businesses and individuals already have an active Trusted Profile, making this a low-barrier entry point for initial KSeF access.
KSeF certificate: a new authentication credential introduced with KSeF 2.0, issued specifically for platform access. This provides an alternative for organizations that do not hold qualified seals or prefer a KSeF-specific credential.
KSeF token: the critical method for automation. A KSeF token enables system-to-system communication without requiring manual authentication for each submission or retrieval. For any business processing more than a handful of invoices per day, token-based access is effectively a requirement.

API Access and Automation

The Polish Ministry of Finance released official KSeF API documentation on June 30, 2025, followed by a test environment on September 30, 2025. These two resources, the API specification and the sandbox, are what ERP vendors and integration platforms need to build and validate their KSeF connectors.

The combination of KSeF tokens and the API is what makes high-volume automation possible. Without token-based API access, every invoice submission or download would require manual intervention through the KSeF web portal. For AP departments receiving hundreds or thousands of invoices monthly, manual retrieval is not a viable long-term workflow. When evaluating KSeF-ready software, verifying that a solution supports token-authenticated API integration should be a primary selection criterion.

For AP teams on the receiving end, FA(3) XML means inbound domestic invoices arrive with a predictable, machine-readable field structure. The benefit is significant, but only if your systems can ingest FA(3) data. If they cannot, you are effectively locked out of the structured data KSeF provides, and your team will still need to process these invoices manually or through extraction tools.

Offline Modes, Invoice Corrections, and KSeF Penalties

KSeF is designed as a centralized, always-on platform, but the Polish Ministry of Finance built in contingency procedures for situations where connectivity or system availability breaks down. Understanding these fallback modes, along with the overhauled correction process and the penalty timeline, is essential for any business operating under the mandate.

KSeF Offline Modes

When a seller cannot connect to KSeF to issue a structured invoice in real time, one of four offline modes applies depending on the cause of the disruption:

Offline Mode	Trigger	Upload Deadline
Offline24	Connectivity issues on the taxpayer's side	Next business day after connectivity is restored
Offline (Service)	Planned KSeF maintenance announced by the Ministry	1 business day after service is restored
Emergency	Official system failure declared by the Ministry of Finance	7 business days after the failure period ends
Total Failure	Critical infrastructure threat affecting KSeF operations	No upload obligation for the duration of the declared period

Invoices issued during any offline period must carry QR codes containing dual verification information, both the seller's details and a hash of the invoice data. This maintains traceability and allows recipients to verify invoice authenticity until the documents are uploaded to KSeF and assigned their permanent KSeF identification numbers.

Corrective Invoices Replace Credit and Debit Notes

As of February 1, 2026, the traditional credit note and debit note framework is eliminated. In its place, KSeF introduces corrective invoices that must directly reference the original invoice's KSeF ID number. This creates a clear, auditable chain between the original document and any subsequent adjustments within the national system.

Buyer-issued correction notes (known as noty korygujące) are no longer valid under the new regime. However, KSeF does provide a mechanism for buyers to propose corrections through the platform, which the seller can then accept or reject. The correction is only finalized once the seller issues a formal corrective invoice through KSeF.

JPK_VAT Reporting Requirements

From February 2026, JPK_VAT returns gain a new mandatory data point: every invoice entry must include either the KSeF ID number or one of three marker codes:

OFF: invoice issued in offline mode (not yet uploaded to KSeF)
BFK: invoice outside KSeF scope (e.g., B2C transactions, exempt supplies)
DI: non-invoice document included in the VAT return

A JPK_VAT submission missing this data for any line item will be rejected outright. This is an immediate operational risk starting February 2026, well before the KSeF penalty grace period ends, because standard VAT sanctions for incorrect or incomplete returns apply from day one. Invoices for transactions involving Annex 15 goods and services above PLN 15,000 carry an additional annotation obligation under Poland's mandatory split payment mechanism, which requires the seller to include a specific MPP notation and the buyer to route payment through a dedicated VAT account.

Penalty Framework and Grace Period

The enforcement timeline is split into two distinct phases:

Throughout 2026 (grace period): No financial penalties are imposed for KSeF-specific violations such as failing to issue invoices through the platform. This window is designed to give businesses time to resolve implementation issues without immediate financial consequences.

From January 1, 2027: Penalties of up to 100% of the VAT amount can be assessed on invoices that were required to be issued through KSeF but were not. This is a significant financial exposure, particularly for high-value B2B transactions.

Critical distinction: The grace period applies only to KSeF-specific obligations. Standard VAT sanctions, for errors in VAT returns, missing documentation, late filings, and similar compliance failures, remain fully enforceable from February 1, 2026. A rejected JPK_VAT return due to missing KSeF ID markers, for example, falls under general VAT enforcement, not the KSeF grace period.

For AP teams receiving invoices, there is an additional consideration: offline-period invoices arrive with temporary identifiers that change once the seller uploads them to KSeF. Your matching and reconciliation processes need to account for this, especially during the early months when connectivity disruptions are more likely.

How KSeF Changes AP Workflows for Invoice Receivers

Most KSeF guides focus on the issuing side of e-invoicing, covering how businesses generate and submit compliant invoices. But for AP departments, the impact on receiving and processing invoices is equally significant and rarely covered. Understanding these workflow changes is essential for finance teams that handle high volumes of incoming invoices from domestic and international suppliers.

Structured Data Extraction from KSeF XML

Invoices received through KSeF arrive as structured FA(3) XML files. This means core invoice data (vendor details, amounts, dates, tax breakdowns, and line items) can be extracted programmatically without manual data entry or traditional OCR. For high-volume AP operations processing hundreds or thousands of domestic invoices monthly, this eliminates a major manual processing step. ERP systems and accounting software with KSeF integration can ingest these structured fields directly, reducing both processing time and transcription errors.

Automatic Archiving and Retention

KSeF stores all invoices for 10 years automatically, satisfying Polish retention requirements with a comfortable margin beyond the standard 5-year statute of limitations. This reduces the document management burden significantly, as AP teams no longer need to maintain separate archives for domestic invoices received through the system. That said, most tax advisors still recommend maintaining private backups as a safeguard against system outages or disputes that require independent verification.

The Mixed-Format Reality AP Teams Face

Even with KSeF fully operational, AP departments will not process invoices from a single source in a single format. The day-to-day reality involves handling invoices from multiple channels simultaneously:

KSeF XML invoices from compliant domestic suppliers
Legacy PDF and paper invoices from the pre-KSeF era that still require processing as part of historical backlogs
B2C invoices that remain outside KSeF, where participation is voluntary only
Foreign supplier invoices from vendors outside Poland that do not use KSeF
Offline-period invoices that arrive in non-standard formats before being uploaded to KSeF after system availability is restored

This mixed-format coexistence is not a temporary transition problem that resolves once KSeF reaches full adoption. Foreign supplier invoices and B2C invoices will permanently remain outside the KSeF system.

Workflow-Level Implications for Mixed-Mode Operations

Operating in mixed mode creates several practical challenges for AP processes:

Three-way matching complexity. KSeF invoices carry a unique KSeF ID that ties directly to the government record, while non-KSeF invoices rely on supplier-assigned numbers. Your matching process needs to handle both identifier types and account for the fact that offline-period invoices may initially carry temporary references that update once uploaded.
Approval routing. Structured KSeF XML invoices can be routed automatically based on parsed fields (vendor, amount, cost center). Unstructured PDFs and scans still require manual review or extraction before routing. Parallel workflows add operational overhead if not consolidated.
Duplicate detection. The same invoice could theoretically arrive via both KSeF and email (if a supplier sends a PDF copy alongside the official KSeF submission). Your system needs rules to identify and flag duplicates across channels.
Audit trail consistency. KSeF invoices have government-backed authenticity and a 10-year archive. Non-KSeF invoices require your own retention and verification processes. Maintaining a unified audit trail across both sources takes deliberate design.

AP teams need extraction capabilities that handle both structured KSeF XML data and unstructured legacy formats within a unified workflow. Tools like AI-powered invoice data extraction process PDFs, scans, and images alongside structured data, handling batches of up to 6,000 mixed-format files with multi-language support including Polish. This covers the documents that fall outside KSeF without replacing the structured data KSeF provides.

Businesses facing similar multi-format challenges from other EU mandates can review how Italy's FatturaPA e-invoicing system and France's parallel e-invoicing mandate are handling the same transition from legacy formats to mandatory structured invoicing.

Your KSeF Readiness Checklist for 2026

Translating regulatory requirements into operational readiness takes structured planning. The following checklist covers every preparation area finance teams and AP departments should address before their applicable compliance deadline.

Determine your compliance phase. Identify whether your business falls into Phase 1 (February 2026, large taxpayers exceeding PLN 200 million in revenue), Phase 2 (April 2026, all other VAT-registered businesses), or Phase 3 (January 2027, micro-entrepreneurs). Regardless of which phase applies to your issuance obligations, you must already be capable of receiving KSeF invoices from suppliers who are live on the platform.
Audit your current invoice formats. Catalog every incoming invoice source across your AP operation. Classify each supplier into one of three categories: those who will transmit through KSeF, foreign suppliers operating outside the Polish system, and any remaining legacy formats such as PDF or paper that still require processing during the transition period.
Evaluate your ERP and accounting integration. Confirm whether your accounting software or ERP system can receive and process FA(3) XML data directly from KSeF. Contact your vendor now about their KSeF integration roadmap, specific module requirements, and expected delivery dates. If your current system lacks a clear path to KSeF compatibility, begin evaluating alternatives.
Set up KSeF authentication. Register for a KSeF authorization token or configure qualified electronic seal and signature authentication for your organization. Use the Ministry of Finance's KSeF test environment to verify your connection, test invoice retrieval, and confirm that your credentials work before the production mandate takes effect.
Update your correction workflow. Replace existing credit note and debit note templates with the corrective invoice process that references original KSeF invoice numbers. Train AP and AR staff on the new procedure, including how to handle corrections for invoices issued during offline periods that carry temporary identification numbers rather than standard KSeF IDs.
Plan for mixed-format processing. Establish a unified workflow for handling KSeF XML invoices alongside non-KSeF documents from foreign suppliers, B2C transactions, and offline-period invoices. This dual-stream reality will persist indefinitely for businesses with international supplier bases. Extraction tools that normalize multiple invoice formats into a single structured output can eliminate the need to maintain parallel processing workflows.
Update JPK_VAT procedures. Ensure your VAT return preparation process captures KSeF identification numbers for every structured invoice and applies the correct marker codes (OFF for offline-period invoices, BFK for invoices outside KSeF scope, DI for non-invoice documents) where a KSeF number is absent. Incomplete or missing KSeF data in JPK_VAT filings will trigger rejection by the tax authority.
Build contingency procedures. Document your organization's offline invoicing process for each failure scenario. This includes QR code generation requirements for Offline24 mode, Service mode, and Emergency mode, along with the mandatory upload timelines that apply once connectivity is restored. Staff who handle invoice issuance should know which mode applies to each situation without needing to consult documentation under pressure.

Poland's mandate is part of a broader wave of structured e-invoicing adoption across the European Union. Businesses already navigating Germany's e-invoicing requirements, Spain's SII and Verifactu e-invoicing obligations, or monitoring mandates in France, Romania, and other member states should consolidate their compliance planning across jurisdictions. The underlying technical standards, particularly EN 16931 and the Peppol framework, overlap significantly, and a unified approach reduces both implementation cost and ongoing maintenance burden.

The 2026 grace period on KSeF penalties exists as a window for fine-tuning compliance processes, not for postponing preparation. Businesses that establish their KSeF workflows now will avoid the penalty exposure that begins January 1, 2027, and those that fully adopt structured invoicing stand to benefit from accelerated VAT refunds of 40 days compared to the standard 60-day period, available to businesses VAT-registered for at least 12 months with a bank account on the White List for refunds up to PLN 3,000. The operational advantage belongs to organizations that treat this transition as a process improvement opportunity rather than a last-minute regulatory obligation.