KSeF E-Invoicing in Poland — What Foreign Companies Need to Know (2026)
Poland is introducing mandatory e-invoicing through KSeF (Krajowy System e-Faktur — National E-Invoice System). From April 2026, every VAT-registered company in Poland must issue and receive invoices through this government-operated platform. Paper invoices and PDF invoices sent by email will no longer be valid for VAT purposes.
For foreign entrepreneurs operating Polish companies, this is a significant operational change. This guide explains what KSeF is, how it works, the implementation timeline, what you need to prepare, and how it affects different business models — from trading companies to SaaS businesses.
What Is KSeF
KSeF is a centralised government platform for issuing, transmitting, and storing structured electronic invoices. It replaces the current system where invoices are created by the seller, sent directly to the buyer (via email, post, or EDI), and reported retrospectively through the monthly JPK filing.
Under KSeF, the process changes fundamentally:
- The seller creates an invoice in the structured XML format defined by the Ministry of Finance
- The invoice is sent to KSeF — not directly to the buyer
- KSeF validates the invoice and assigns it a unique identification number (numer KSeF)
- The buyer receives the invoice through KSeF — they access it via the platform using their NIP
- KSeF stores the invoice for 10 years — it becomes the legally binding version
The invoice stored in KSeF is the original. Any version you print, email, or export is a copy. This means the government has real-time access to every invoice issued by every VAT-registered company in Poland — a level of transparency that is unprecedented in EU tax administration.
Implementation Timeline
KSeF implementation has been postponed several times since its original announcement. The current mandatory dates are:
| Date | Who | Obligation |
|---|---|---|
| February 2026 | Large companies (revenue > PLN 200M) | Mandatory KSeF for issuing and receiving invoices |
| April 2026 | All VAT-registered companies | Mandatory KSeF for issuing and receiving invoices |
The voluntary use of KSeF has been available since January 2022. Companies that started using KSeF early have had time to test integrations and resolve technical issues. For companies that have not yet prepared, the April 2026 deadline is approaching fast.
There are no exemptions for foreign-owned companies. If your company is VAT-registered in Poland — regardless of where the owners or directors are based — KSeF is mandatory.
What Changes for Your Company
The shift to KSeF affects several aspects of how your company handles invoicing. Here is what changes in practice.
Issuing Invoices
Every sales invoice must be generated in the KSeF XML schema and submitted to the platform before it is considered issued. You can no longer create a PDF invoice in your accounting system and email it to the client. The invoice must pass through KSeF first.
In practice, this means your accounting software (or your accountant’s system) must have a direct integration with the KSeF API. The software generates the XML, sends it to KSeF, receives the confirmation number, and only then is the invoice considered legally issued.
Receiving Invoices
Purchase invoices from your Polish suppliers will also arrive through KSeF. Instead of receiving invoices by email, your company (or your accountant) downloads them from the KSeF platform. This applies to all domestic transactions between VAT-registered entities.
For invoices from foreign suppliers (non-Polish), KSeF does not apply — those continue to be received directly (email, EDI, or other channels).
Invoice Format
KSeF uses a structured XML format called FA(2). This is not a simple PDF or CSV — it is a detailed, field-by-field electronic document with mandatory and optional elements defined by the Ministry of Finance. The schema includes over 300 fields, though most standard invoices use only a fraction of them.
You do not need to understand the XML structure yourself. Your accounting software or accountant handles the technical generation. What matters is that every invoice contains the required data fields — seller and buyer NIP, item descriptions, VAT rates, amounts — in the exact format KSeF expects.
Invoice Numbering
Each invoice submitted to KSeF receives a unique KSeF identification number. This number coexists with your company’s own invoice numbering system. Both numbers should appear on invoices you share with clients — your internal number for your records, and the KSeF number as proof of valid issuance.
JPK Filing
Currently, your company files a monthly JPK_V7 report that includes all invoice data. With KSeF, the government already has the invoice data in real time — so the JPK filing process is expected to be simplified over time. However, for now, monthly JPK filing remains mandatory alongside KSeF. Your accounting provider handles both.
How KSeF Affects Different Business Models
The practical impact of KSeF depends on your company’s business model and invoicing volume.
Trading and Import/Export Companies
For trading companies, KSeF changes are relatively straightforward. Most invoices are B2B (business to business), issued through accounting software that your provider already uses. The main adjustment is ensuring the software has KSeF API integration. If your accountant uses a modern Polish accounting system, this is typically handled through a software update.
One important detail: customs invoices and documents (SAD, import declarations) are separate from KSeF. Customs documentation follows its own electronic system. KSeF applies only to commercial invoices between business entities.
SaaS and Digital Services Companies
For SaaS companies, KSeF creates a specific challenge. Many SaaS businesses automate invoicing through platforms like Stripe, Paddle, or custom billing systems. These platforms generate invoices automatically when a subscription is charged.
Under KSeF, invoices generated by Stripe or similar platforms are not automatically valid for Polish VAT purposes — they must be issued through the KSeF system. This means one of two approaches:
- Mirror invoicing: Your accounting system receives data from Stripe and issues a corresponding KSeF-compliant invoice for each transaction
- Direct integration: Your billing platform integrates with the KSeF API directly (availability depends on the platform)
For B2C invoices to individual consumers (not businesses), the rules are slightly different — consumer invoices may have transitional provisions. However, any invoice where the buyer provides a NIP (tax ID) must go through KSeF. Your accounting provider should assess which of your invoices fall under KSeF obligations and set up the appropriate workflow.
Amazon and E-Commerce Sellers
Amazon sellers face a particular complexity. Amazon issues invoices on behalf of sellers through its VAT Calculation Service (VCS) in some configurations. Under KSeF, these invoices may need to be reconciled with KSeF-issued invoices from your Polish company. The exact requirements depend on your Amazon account setup and the markets where you sell.
For sellers using the Amazon FBA model through Poland, coordination between Amazon’s invoicing system and your Polish accounting system is essential before the April 2026 deadline. LEXCARTA works with Amazon sellers to map their invoicing workflows and ensure KSeF compliance.
Dormant and Low-Activity Companies
Even if your company has minimal activity, KSeF applies to any invoice you issue or receive. If your company issues even one invoice per month (e.g., re-invoicing the registered address fee to a related entity), that invoice must go through KSeF. For dormant companies that issue no invoices at all, KSeF has no practical impact — but the system must be accessible if activity resumes.
How to Prepare
Preparation for KSeF is primarily the responsibility of your accounting provider. Here is what needs to be in place before the April 2026 deadline.
1. Confirm Your Accountant Is KSeF-Ready
Your accounting provider must have software with active KSeF API integration. This is not optional — without it, they cannot issue or receive invoices on your behalf. Ask your accountant directly: “Is your system integrated with KSeF? Can you issue and download KSeF invoices for my company?” If the answer is unclear, consider switching providers before the deadline.
LEXCARTA’s accounting team uses KSeF-integrated systems as standard. For all clients on our compliance and accounting program, KSeF readiness is included — no separate setup fee.
2. Set Up KSeF Access for Your Company
Your company needs an active KSeF account. Access is granted through the company’s authorised representative — typically the director or an authorised accountant. Authentication uses a qualified electronic signature, trusted profile (Profil Zaufany), or authorisation token generated through the KSeF platform.
For foreign directors who do not have a Polish trusted profile, a qualified electronic signature is the standard authentication method. This is the same e-signature used for remote company management — available through providers like Certum (SimplySign) and obtainable via video verification without visiting Poland. If you already have an e-signature from your company formation, it works for KSeF access as well.
3. Authorise Your Accountant in KSeF
Your accounting provider needs authorisation to issue and download invoices through KSeF on your company’s behalf. This is done through the KSeF platform — you (or your director) grant specific permissions to the accountant’s NIP or personal identifier. LEXCARTA handles this authorisation process as part of compliance onboarding.
4. Review Your Invoicing Workflow
If your company uses automated invoicing (Stripe, WooCommerce, custom billing), assess how these invoices will be handled under KSeF. Your accounting provider should map the workflow: which invoices must go through KSeF, which are exempt (foreign suppliers, consumer invoices under transitional rules), and how automated billing data flows into the KSeF-compliant accounting system.
Penalties for Non-Compliance
The Ministry of Finance has announced a penalty framework for KSeF non-compliance. After the mandatory implementation date:
- Invoices issued outside KSeF will not be valid for VAT purposes — the buyer cannot deduct input VAT from an invoice that was not issued through the platform
- Financial penalties may be imposed for systematic non-compliance — the exact amounts are defined in the amended VAT Act
- Buyer risk: If your company receives an invoice that was not issued through KSeF (from a Polish VAT-registered supplier), you may not be able to deduct the VAT — creating a real financial cost
The penalty regime is expected to include a transitional grace period in the first months after mandatory implementation. However, relying on grace periods is not a compliance strategy. Companies should be fully operational in KSeF before the deadline.
KSeF and Cross-Border Invoicing
Cross-border invoicing is where KSeF creates the most confusion for international companies. The rules vary depending on the type of transaction, the buyer’s status, and which VAT scheme applies.
Intra-EU B2B (Reverse-Charge)
When your Polish company sells goods or services to a business in another EU country under the reverse-charge mechanism, the invoice must be issued through KSeF. The fact that the buyer is in Germany, France, or any other EU country does not exempt the invoice from KSeF — the obligation follows your company’s Polish VAT registration.
The buyer can access the invoice through KSeF’s cross-border features, or you can provide them with a PDF copy. Either way, the KSeF version is the legally binding original. In practice, most EU business clients will expect a PDF or EDI copy alongside the KSeF issuance — your accounting system should handle both outputs automatically.
Exports to Non-EU Clients (B2B)
Invoices to business clients outside the EU — USA, UK, UAE, Turkey, China — must also be issued through KSeF. These are typically zero-rated for VAT purposes (export of services or goods), but the KSeF requirement still applies because the invoice is issued by a Polish VAT-registered entity. Your non-EU client does not need KSeF access — they receive a PDF copy. The original stays in KSeF.
Invoices from Foreign Suppliers
Invoices you receive from suppliers outside Poland — whether EU or non-EU — are not subject to KSeF. Your German supplier, Chinese manufacturer, or US software vendor continues to send invoices through traditional channels (email, EDI, postal). These invoices are entered into your Polish accounting system and reported in your monthly JPK filing as before. KSeF applies only to invoices issued by Polish VAT-registered entities.
OSS Transactions (B2C Cross-Border)
This is important for e-commerce sellers and SaaS companies selling to individual consumers across the EU. If your company reports B2C cross-border sales through the OSS (One-Stop Shop) scheme, the invoicing rules are different from standard domestic transactions.
Under OSS, your company applies the VAT rate of the consumer’s country and reports all cross-border B2C sales in a single quarterly OSS return filed in Poland. The key question is: do these OSS invoices need to go through KSeF?
The current position is that invoices documented for OSS purposes — specifically B2C sales to consumers in other EU member states — are not required to be issued through KSeF. This is because OSS transactions are governed by a separate EU-wide reporting framework, and the invoicing rules of the consumer’s country apply rather than Polish domestic invoicing rules.
However, there are nuances:
- B2C sales to Polish consumers — these are domestic transactions, not OSS. Standard KSeF rules apply. If the buyer requests an invoice with their NIP, it must go through KSeF.
- Mixed sellers — if your company sells both B2B (reverse-charge) and B2C (OSS) across the EU, the B2B invoices must go through KSeF while the B2C/OSS invoices follow OSS rules. Your accounting system must distinguish between these flows.
- Marketplace sellers — if Amazon or another marketplace is the deemed supplier for VAT purposes (common for non-EU sellers), the invoicing obligations may shift. Your specific setup determines which invoices your company must issue through KSeF.
Given the complexity, Amazon and e-commerce sellers should have their accounting provider map exactly which transactions fall under KSeF and which are reported through OSS before the April 2026 deadline.
IOSS Transactions (Low-Value Imports to EU Consumers)
IOSS (Import One-Stop Shop) covers a specific scenario: goods imported from outside the EU and sold directly to EU consumers, where the consignment value does not exceed €150. Under IOSS, VAT is collected at the point of sale rather than at the border.
Invoices related to IOSS transactions follow a similar logic to OSS — they are governed by the IOSS framework rather than Polish domestic invoicing rules. The IOSS return is filed monthly and covers all EU member states where consumers received goods. These invoices are generally not required to go through KSeF, as the transaction is documented within the IOSS reporting system.
As with OSS, the rules may evolve as KSeF implementation matures. Your accounting provider should monitor any regulatory updates and adjust your invoicing workflows accordingly.
Summary: KSeF Applicability by Transaction Type
| Transaction Type | KSeF Required? | Notes |
|---|---|---|
| Domestic B2B (Polish buyer with NIP) | Yes | Standard KSeF obligation |
| Intra-EU B2B (reverse-charge) | Yes | Issued by Polish VAT entity |
| Export B2B to non-EU | Yes | Zero-rated, but KSeF still applies |
| B2C to Polish consumer (with NIP) | Yes | Domestic transaction |
| B2C cross-border via OSS | No* | Reported through OSS framework |
| B2C low-value imports via IOSS | No* | Reported through IOSS framework |
| Invoices FROM foreign suppliers | No | Not issued by Polish entity |
* Subject to evolving regulatory guidance. Monitor updates through your accounting provider.
KSeF Through LEXCARTA
For companies on LEXCARTA’s accounting and compliance program, KSeF preparation and ongoing compliance is included as standard:
- KSeF account setup and authorisation for your company
- KSeF-integrated accounting software — invoices issued and received through the platform
- Workflow assessment for companies with automated billing (Stripe, marketplace integrations)
- Ongoing management — all invoicing handled through KSeF as part of monthly accounting
- E-signature coordination — if your director needs a qualified e-signature for KSeF access, we arrange it (€350, valid 3 years, video verification)
If you are forming a new company or already have a Polish entity that is not yet KSeF-ready, check your eligibility or schedule a consultation to assess your readiness before the April 2026 deadline.
Frequently Asked Questions
Can I still send PDF invoices to clients?
You can send a PDF copy of the invoice to clients for convenience, but the legally binding version is the one stored in KSeF. After April 2026, an invoice that was not issued through KSeF is not valid for VAT deduction purposes.
Does KSeF apply to my company if I only sell to foreign clients?
Yes. If your company is VAT-registered in Poland, all invoices it issues must go through KSeF — regardless of where the buyer is located. The obligation is tied to your Polish VAT registration, not to the buyer’s country.
What if my accounting provider is not KSeF-ready?
Switch providers before April 2026. An accountant without KSeF integration cannot issue valid invoices for your company after the mandatory date. This will directly affect your ability to conduct business and deduct input VAT.
Does KSeF replace JPK filing?
Not yet. Currently, both KSeF invoicing and monthly JPK filing are required. The government has indicated that JPK may be simplified or partially replaced by KSeF data in the future, but for now both obligations run in parallel.
Is KSeF mandatory for companies using the Estonian CIT (ryczałt)?
Yes. KSeF applies to all VAT-registered companies in Poland, regardless of which CIT regime they use. The obligation is linked to VAT registration, not to the corporate tax model.