The year 2026 arrives, and Poland changes the way B2B invoices are issued, received, and stored. Now, the Krajowy System e-Faktur (KSeF) becomes the mandatory central channel. For financial managers and CFOs of large international groups operating there or invoicing Polish suppliers and companies, this means reviewing processes, updating ERP systems, negotiating contractual changes, and ensuring real-time fiscal traceability. Let's take a look at what the new law on electronic invoicing in Poland, the deadlines you need to note, how to prepare for implementation, and what operational impact the new digital invoicing will have on your company.
What is KSeF and why is it changing electronic invoicing in Poland?
To begin with, the KSeF is where Poland's new electronic invoicing system will be consolidated. It is a centralized system where structured invoices are issued, recorded, and stored. With it, the Polish government is moving from a "post-audit" invoicing model to a registration model that offers the tax authorities greater traceability and reduces VAT fraud.
Therefore, this new electronic invoice provides:
- Better VAT traceability. The Administration obtains structured data in near real time, reducing the risk of discrepancies in deductions.
- Less scope for improper invoices. Issuing invoices through KSeF limits unregistered "offline" issuance.
- Grace periods. The government has announced that it will be lenient during 2026 (reducing penalties for formal errors) so that companies can adapt. However, this does not replace the obligation to adapt.
Mandatory dates and schedule
As for the entry into force of electronic invoicing in Poland, here is a table with the dates marked in red on the calendar:
| Date | What affects | To whom |
| February 1, 2026 | Mandatory KSeF (phase 1) | Large companies with a turnover in 2024 exceeding 200 million zlotys (approximately €47 million). |
| April 1, 2026 | Mandatory for most companies (B2B and B2G) | Other taxpayers registered in the VAT (except for temporary exceptions). |
| 2026 (until December 31) | Grace period for penalties/errors | The government is applying temporary extensions to fines for errors in invoices and bank field requirements. |
| January 1, 2027 | Entry into force for microenterprises (deferred) | Microenterprises with very low monthly sales (temporary exemptions). |
Technical and legal requirements: what a CFO needs to monitor
In turn, this new billing system requires compliance with both technical and legal requirements:
- Structured format FA(3). KSeF uses a structured data schema, and invoices must comply with it in order to be registered.
- Issuance via KSeF. Now, the invoice is generated and sent to the system to obtain an identifier and appear in the official registry. Only then will it be valid.
- KSeF registration and number. Each invoice in KSeF receives a unique identifier that must appear in accounting records and reconciliations.
- ERP/FP&A integration. ERPs must be able to generate FA(3), communicate with KSeF, and store the metadata returned by the system.
- Storage and archiving. KSeF acts as the official archive, but accounting retention obligations remain in force.
- B2G and B2B. For invoices to the public sector (B2G) or other companies (B2B), the requirement applies according to the schedule, while B2C invoices are excluded (although they may use it voluntarily).
- Security and access. Proper management of certificates, roles, and permissions must be applied for mass issuance.
In any case, it is advisable to stay abreast of any legal developments that may arise. Some subsequent milestones (e.g., requirement for payment references in transfers) have been planned for later phases in 2026.
How can this electronic invoice be implemented in a multinational company?
On a practical level, we show you how to implement electronic invoicing in a multinational company operating in Poland. Or, rather, what aspects you need to take into account when doing so.
- Governance & Project. Appoint a CFO and a cross-functional team: tax, IT, ERP, treasury, legal. At the same time, create a project plan with milestones: PoC FA(3), KSeF test, go-live by subsidiary, etc.
- Impact analysis. Analyze the inventory of billing flows (B2B, B2G, intercompany), as well as the monthly volume and peaks (queue sizing and throttling).
- ERP & Connectivity. Update your invoice generator to FA(3), with a communication module with KSeF (APIs or connectors) and a trial plan in the KSeF sandbox environment.
- Controls & Compliance. Try automatic reconciliations with a KSeF identifier and procedures for rejections or corrections.
- Treasury and contracts. Review supplier and customer SLA contracts for their impact on payment terms.
- Training & Operations. Train your teams and document the process and incidents.
And on a technical level? Recommendations for the IT department
- Choose integration mode. That is, use a direct API with KSeF or integrate a service provider (if you opt for SaaS). Here, evaluate latency, SLA, and certifications.
- FA(3) format. Adapts field mappings (items, taxes, contract reference, discounts, taxes separated by type, etc.) to the FA(3) schema.
- Volume tests. Perform stress tests with peak volumes and simulated errors.
- Monitoring and alerts. Design and implement dashboards that you can use to analyze shipments, acceptance, and rejection by country and subsidiary company.
- Fallbacks and exceptions. Define workflows for rejected invoices: corrected resubmission, issuance of credit notes, or use of other mechanisms permitted by regulations.
Most common risks of electronic invoicing and how to mitigate them
Although the implementation of KSeF is a technically feasible project, there are also operational risks that could affect the business. Therefore, CFOs should anticipate or prevent the following problems:
Blocking of invoice issuance due to integration errors.
The connector between the ERP and KSeF may fail and prevent invoices from being issued or delay collections.
How to mitigate it: Perform end-to-end testing in a sandbox, replicate real volume peaks, and agree on a contingency plan with the provider. Having a technical team on call during the first few weeks also shortens response times.
Rejections due to errors in the FA(3) schema
Many companies underestimate the complexity of properly mapping their information to the FA(3) format. A single poorly structured field causes systematic rejections.
How to mitigate this: Implement a pre-validator in the ERP or billing platform. This way, errors are detected before the invoice is sent to KSeF. In addition, documenting "error patterns" speeds up incident resolution.
Operational conflicts with customers who continue to request PDFs
In many sectors, there are still customers who, out of habit or due to outdated systems, want to continue receiving a PDF invoice. In 2026, this PDF can be sent as a copy, but it does not replace the invoice registered in KSeF, which can lead to misunderstandings and delays in payments.
How to mitigate this: review contracts and communicate in advance how the process will work once it becomes mandatory. Ideally, send the informational PDF along with the KSeF identifier to facilitate internal registration.
Bank reconciliation issues
The requirement to include identifiers on payments and invoices can lead to discrepancies, especially if treasury and accounting are not synchronized.
How to mitigate this: Carefully review the payment reference settings in your banking systems and ensure that they match the fields required by KSeF. Automating reconciliation minimizes errors and reduces the impact on accounting closings.
Excessive dependence on the supplier or local technical team
In multinational companies, it is common for the Polish subsidiary to depend on central IT for any adjustments. This can become a bottleneck with legal changes or schema updates.
How to mitigate this: define responsibilities between local IT and corporate IT and include commitments for continuous updating of the FA(3) schema and KSeF endpoints in the contract with the supplier.
easyap in electronic invoice management in Poland
As a platform for automating financial processes and an expert in multinational e-invoicing, easyap allows you to easily and securely integrate your invoicing system with KSeF, respecting your internal workflows and without requiring technical effort from your teams. With easyap, you can, among other things:
- Issue and receive FA(3) electronic invoices without modifying your ERP.
- Connect directly to KSeF through certified APIs and monitor the status of each invoice in real time.
- Apply automatic validations to avoid rejections, formatting errors, or incidents in deadlines.
- Maintain a centralized historical archive, accessible for audits and reconciliations.
- Manage large volumes of invoicing without bottlenecks and with full traceability.
- Integrate all countries and e-invoicing regulations where you operate.
In summary, electronic invoicing in Poland, mandatory by 2026, marks a turning point. Although the transition may seem complex, it is an opportunity to automate processes, reduce costs, and increase fiscal control. With easyap, companies can face the change with confidence, speed, and without disruptive impacts on their systems. Contact us and let's work on a secure, scalable implementation tailored to your operations.
