KSeF Poland e-invoicing 2026: a guide for foreign firms

What KSeF is, in plain English

KSeF stands for Krajowy System e-Faktur, the National e-Invoicing System run by Poland’s Ministry of Finance. Business-to-business invoices are no longer PDFs sent by email. They are structured invoices (faktura ustrukturyzowana): data in a fixed format that is sent to KSeF first and reaches the buyer through the system.

According to the Ministry of Finance’s published materials, the current structured invoice schema is called FA(3), and technical documentation for software providers is available at ksef.podatki.gov.pl. You will rarely touch the schema yourself, but you need invoicing software that supports it.

A practical example: a Dutch-owned design studio set up as a Polish limited company invoices a Warsaw retailer every month. Its invoicing software sends each invoice to KSeF. The retailer’s accountant then downloads it from KSeF rather than from an email attachment.

Does KSeF apply to your business?

This guide is written for businesses that are Polish VAT taxpayers: a Polish company owned by foreign shareholders, a branch-style operation run from Poland, or a foreigner running a Polish sole proprietorship. If that describes you, the dates below apply to you exactly as they apply to Polish-owned firms. Nationality and ownership make no difference.

Two situations are outside what this guide can answer reliably. First, a foreign company that is registered for Polish VAT but has no establishment in Poland. Second, invoices to private consumers (B2C). How KSeF applies in those cases is a separate question, so confirm it with a Polish tax adviser before you rely on any general timeline, including this one.

KSeF timeline for 2026 and 2027

The current schedule comes from the amendment to the Polish VAT Act of 5 August 2025, published in the Journal of Laws as Dz.U. 2025 poz. 1203. Earlier start dates in July 2024 and January 2025 were postponed because of technical problems. If a colleague or an older blog post mentions those dates, they are out of date.

Keep two obligations apart: receiving invoices and issuing invoices. Receiving started for everyone on the same day. Issuing is phased by business size.

Receiving invoices: the obligation that already applies

Since 1 February 2026, every VAT taxpayer has to receive invoices through KSeF, even if it does not yet have to issue them there. Foreign-owned firms often miss this, because nothing visibly changes on their side: suppliers simply start sending invoices through the system.

In practice, the invoice from your office landlord, your IT supplier or your wholesaler sits in KSeF, even if the supplier also emails you a readable copy. You, or your accounting office, need access to KSeF to download those invoices and book them.

If your finance team works from another country, decide who in Poland or abroad is responsible for pulling purchase invoices from KSeF and passing them to bookkeeping. A missing purchase invoice is easy to overlook when the email trail no longer tells the whole story.

According to Polish accounting press, new JPK_VAT structures with KSeF-related markers apply from the February 2026 reporting period. JPK_VAT is Poland’s electronic VAT reporting file, normally prepared by your accountant, so ask whether this change has been handled.

• Receiving through KSeF applies to all VAT taxpayers from 1 February 2026.
• An emailed PDF from a supplier does not replace access to KSeF.
• Put in writing who downloads purchase invoices: you, your accounting office or your software.

The PLN 10,000 relief for the smallest businesses

Under the 2025 amendment, taxpayers whose monthly sales documented by invoices do not exceed PLN 10,000 gross may keep issuing invoices outside KSeF until 31 December 2026. Everyone else below the PLN 200 million threshold has been issuing in KSeF since 1 April 2026.

Example one: an expat translator running a Polish sole proprietorship invoices two agencies for a combined PLN 6,000 gross a month. The relief can apply until the end of 2026. Example two: a small software company owned from abroad bills Polish clients PLN 40,000 gross a month. No relief applies, and it should have been issuing in KSeF since 1 April 2026.

The relief is temporary. From 1 January 2027 everyone issues in KSeF. The detailed conditions, such as what happens if you exceed PLN 10,000 in a single month, are worth confirming with your accountant before you build a plan around them.

If your business is VAT-exempt, do not assume KSeF is irrelevant. The penalty rules also mention invoices that show no VAT amount, so check your position with an accountant.

Penalties: what applies and from when

Administrative penalties for breaking the KSeF rules, set out in Article 106ni of the Polish VAT Act, have been postponed. Polish accounting and business press consistently report that they apply from 1 January 2027, so no administrative penalties under the VAT Act are imposed for KSeF in 2026.

After that date, according to the same sources, the penalty can be up to 100% of the VAT shown on an invoice issued outside KSeF. For invoices without a VAT amount, it can be up to 18.7% of the total amount due.

The penalty is imposed by a decision of the head of the tax office (naczelnik urzędu skarbowego), is payable within 14 days of the decision, and can be reduced or waived depending on how serious the breach was.

No administrative penalties in 2026 does not mean invoice errors are harmless. If an invoice was not issued, or was issued with incorrect data, discuss the possible consequences with your accountant or tax adviser.

Access, software and outages

Access. Your business has to authenticate in KSeF, and if an accounting office or an employee handles invoices, you need to settle who acts on the company’s behalf and with what rights. The Ministry of Finance describes the current login and authorisation options on ksef.podatki.gov.pl. Check there or agree the setup with your accounting office rather than following older forum posts.

Software. Invoices are issued in KSeF from invoicing or accounting software connected to the system. Ask your provider three direct questions: does it send invoices to KSeF, does it download purchase invoices, and does it support the FA(3) schema? Group-level ERP systems configured abroad deserve a specific check, because a Polish entity may need a local connector.

Where invoices start in several places, for example a CRM, a booking system and a spreadsheet, it is usually cheaper to connect them to one KSeF-ready invoicing tool than to retype data. Synelo builds that kind of integration as a project for small and medium businesses.

Outages. According to industry materials, the rules provide separate procedures for when your internet connection fails or KSeF itself is unavailable, described among other things as offline24 mode and emergency mode. Agree the details with your software provider and accountant before you need them.

• Who has KSeF access, and can the accounting office act for you?
• Does your software issue in KSeF and download purchase invoices?
• Does it support the current FA(3) schema?
• What do you do when the internet or KSeF is down?

Polish terms you will meet

Accountants and software menus in Poland use these Polish terms even when you speak English.

• KSeF (Krajowy System e-Faktur): the national e-invoicing platform of the Ministry of Finance.
• Faktura ustrukturyzowana: a structured invoice, the data-based invoice that goes through KSeF.
• FA(3): the current version of the structured invoice schema.
• Ustawa o VAT: the Polish VAT Act; the KSeF penalties are in Article 106ni.
• JDG (jednoosobowa działalność gospodarcza): a sole proprietorship, the usual form for self-employed people.
• NIP: the Polish tax identification number of a business.
• Biuro rachunkowe: an accounting office, the outsourced bookkeeper most small firms use.
• Naczelnik urzędu skarbowego: the head of the local tax office, who issues penalty decisions.
• JPK_VAT: the electronic VAT reporting file submitted to the tax authority.

What to do now: six steps

It is October 2026. Receiving through KSeF already applies, most businesses already issue there, and the micro relief has under three months left. A sensible order of work:

1. Confirm your group. Work out your monthly gross invoiced sales. Above PLN 10,000, issuing in KSeF has applied to you since 1 April 2026, so check that it is actually happening.

2. Sort out access. Make sure you and your accounting office can log in to KSeF, and that someone named is responsible for downloading purchase invoices.

3. Check your software. Get written confirmation of KSeF and FA(3) support from your provider, including any group ERP. If the answer is unclear, change tools this year.

4. Issue test invoices. Run a handful of real invoices through KSeF before 2027 so you understand the full flow, including corrections.

5. Write an outage procedure. Agree with your software provider and accountant what happens when the internet or KSeF is down. One page is enough.

6. Talk to a Polish accountant. Confirm your group, the relief conditions and any exposure from 2026 errors before penalties start on 1 January 2027.