KSeF for a JDG in Poland: what it is, from when and how to issue invoices

KSeF, the National e-Invoicing System (Krajowy System e-Faktur), is the state system for issuing, sending, receiving and storing structured invoices. From 2026 it covers all business owners in stages, including a JDG (a sole trader’s business, jednoosobowa działalność gospodarcza). Below: what a structured invoice is, from when KSeF applies to your JDG, how to issue an invoice in it and how to download purchase invoices, what the KSeF number is, what happens with consumers and clients abroad, how offline24 mode works and which free state tools you can use.

The rules and deadlines were checked on ksef.podatki.gov.pl and biznes.gov.pl on 30 September 2026.

KSeF — what a structured invoice is

An invoice issued in KSeF is a structured invoice (faktura ustrukturyzowana; in the Ministry of Finance’s announcements also an e-Faktura). It’s an XML file following the FA(3) schema, sent to the system, to which KSeF has assigned a unique number. A buyer with a NIP (the tax identification number) finds it in the system, and KSeF stores it for 10 years, counted from the end of the year in which it was issued.

A structured invoice isn’t the same as an electronic invoice (faktura elektroniczna). Biznes.gov.pl stresses that the two terms aren’t synonyms:

An invoice issued in KSeF can’t be edited, cancelled or deleted. You correct a mistake only with a corrective invoice (faktura korygująca), also in KSeF — more on this in the article on invoice types.

From when KSeF is mandatory for a JDG

The legal form doesn’t matter: the obligation applies to every taxpayer who has to issue an invoice — both an active VAT payer and a VAT-exempt one. According to ksef.podatki.gov.pl, the deadlines came in stages:

So most JDGs have been in KSeF since 1 April 2026. Only the smallest sellers have an exception until the end of the year.

The PLN 10,000 a month limit until the end of 2026

According to ksef.podatki.gov.pl, until 31 December 2026 you can issue invoices outside KSeF — on paper or electronically, e.g. as a PDF — if in a given month the total value of sales documented by such invoices doesn’t exceed PLN 10,000 gross. You calculate the limit:

• monthly, by the invoice’s date of issue,
• with VAT, that is on gross amounts,
• only from invoices that would normally have to go into KSeF. You don’t count invoices for consumers or receipts with the buyer’s NIP (paragon z NIP) up to PLN 450 towards the limit.

If you exceed the limit in a given month, you issue the invoice that exceeds it, and all the following ones, in KSeF.

The PLN 10,000 limit only exempts you from issuing invoices in KSeF. You have to receive invoices from suppliers who issue them in the system from 1 February 2026 — whatever your sales.

From 1 January 2027 this exception disappears: from then on every JDG, even one with a single invoice a month, issues invoices for businesses in KSeF. On the same day, receipts with the buyer’s NIP stop being invoices — the article on invoice types covers this.

Penalties for not using KSeF

For an invoice issued outside KSeF despite the obligation, the head of the tax office may impose a financial penalty, as art. 106ni of the VAT Act provides: up to 100% of the VAT on the invoice, or up to 18.7% of the total amount due if the invoice shows no VAT. Under the current regulations the penalties apply to breaches from 1 January 2027; they aren’t imposed for 2026.

No penalty doesn’t mean no obligation: sales documented outside KSeF are still subject to VAT, and the buyer may treat such an invoice as a warning sign.

How to get access to KSeF

The Ministry of Finance describes it as a few steps:

1. Check your deadline — 1 April 2026 or, with the PLN 10,000 limit, 1 January 2027.
2. Choose a tool — the ministry’s free tool or software integrated with KSeF 2.0.
3. Log in. A JDG has access straight away, through Profil Zaufany (the state’s free trusted e-identity) or a qualified electronic signature; it doesn’t file the ZAW-FA form (the KSeF authorisation form), which concerns companies without a qualified seal.
4. Generate a KSeF certificate, if you need one — it’s used for logging in (type 1) and for offline invoices (type 2).
5. Grant permissions, if someone issues invoices for you — e.g. an accounting office. You can grant them to the whole office, and it will name its staff.

A PESEL alone isn’t enough to log in: you need Profil Zaufany, a qualified signature, a qualified seal, a KSeF token or a KSeF certificate.

Issuing an invoice in KSeF

Issuing an invoice in KSeF looks like this:

1. You log in to a tool — the Aplikacja Podatnika KSeF (the Ministry’s free KSeF app), the Aplikacja Mobilna KSeF, e-mikrofirma or integrated software.
2. You fill in the invoice. The tool turns it into an XML file in the FA(3) structure.
3. The invoice goes into KSeF, which checks it and assigns it a KSeF number.
4. From that moment the invoice is issued and received by a buyer with a Polish NIP. You don’t have to send it by email or wait for the client to accept it.

A structured invoice contains the same details the VAT Act requires on every invoice. The schema also has additional fields (e.g. contact details), but they aren’t mandatory.

KSeF doesn’t send notifications of new invoices — neither to you nor to your client. It’s worth telling regular clients that the invoice is waiting in the system, especially in the first months.

Downloading invoices from KSeF

You get purchase invoices from suppliers who issue them in KSeF in the system from 1 February 2026. An invoice is deemed received the moment KSeF assigns it a number — even if nobody has opened it yet.

You download invoices from KSeF in two ways:

• Manually — you log in to the Aplikacja Podatnika KSeF or the Aplikacja Mobilna KSeF and browse the invoices issued to your NIP.
• Automatically — software integrated with KSeF regularly checks whether new invoices have appeared, and downloads them.

A supplier who still uses the PLN 10,000 limit can send you an invoice as a PDF or on paper until the end of 2026. Such an invoice still gives you the right to deduct VAT, if the usual conditions of art. 86 of the VAT Act are met.

The KSeF number — what it is and where you’ll use it

The KSeF number is the identifier the system assigns to every structured invoice. It isn’t part of the XML file — KSeF returns it in the UPO (the official confirmation of receipt, Urzędowe Poświadczenie Odbioru). On a visualisation of the invoice, e.g. in a PDF for the client, it appears as a QR code with a caption in the form of the KSeF number. The code lets you check whether the invoice is in the system.

You’ll need the KSeF number in three places:

• A corrective invoice for an invoice from KSeF gives the KSeF number of the invoice it corrects.
• JPK_V7M / JPK_V7K (the monthly VAT file with the return / the quarterly one) — an active VAT payer enters the invoice’s KSeF number in the record, or a marking when the invoice has none (e.g. BFK for an invoice issued outside KSeF). Details in the article on JPK_VAT.
• A bank transfer — from 1 January 2027 a payment between active VAT payers for an invoice from KSeF, and also a transfer under the split payment mechanism (mechanizm podzielonej płatności, MPP), gives the invoice’s KSeF number (art. 108g and art. 108a ust. 3 pkt 3 of the VAT Act).

KSeF and invoices for private individuals and clients abroad

A consumer

Invoices for private individuals who don’t run a business don’t have to go into KSeF. You can issue them there voluntarily, but a consumer won’t receive the invoice from the system — you pass it to them in an agreed way, e.g. as a PDF. An invoice for a business owner buying for their own private use is voluntary too.

A client abroad

As ksef.podatki.gov.pl explains, if your JDG is established in Poland, you issue an invoice for a foreign business client in KSeF — the obligation depends on the seller, not the buyer. A client without a Polish NIP won’t receive it from the system, though, so you pass it to them in an agreed way, e.g. as a PDF with the QR code and the KSeF number. Excluded from KSeF are, among others, invoices of taxpayers with no seat or fixed establishment in Poland, and invoices under the non-Union OSS and IOSS schemes. Selling services to EU clients and the OSS (the EU One Stop Shop for VAT) scheme are described in the article on VAT-UE and OSS.

Offline24 mode and the other offline modes

The basic mode is online: the invoice goes into KSeF in real time. Alongside it there are three special modes:

You can use offline24 mode even when you have no connection problems at all. An offline invoice, passed to the client before it goes into KSeF, has two QR codes: the first captioned „OFFLINE” for verifying the invoice’s details, the second captioned „CERTYFIKAT” (certificate) for verifying the issuer. The second code needs a type 2 KSeF certificate generated in advance — it’s worth having one before the first outage happens.

The free Aplikacja Podatnika KSeF and e-mikrofirma

You don’t need paid software for KSeF. The Ministry of Finance provides free of charge:

• the Aplikacja Podatnika KSeF — online: issuing and browsing invoices, managing permissions, tokens and certificates, downloading UPOs,
• the Aplikacja Mobilna KSeF — for a smartphone, from 1 February 2026: issuing and receiving invoices, previews, drafts,
• e-mikrofirma (the Ministry’s free invoicing and records tool) in e-Urząd Skarbowy (the tax office’s online portal) — you issue and receive invoices in KSeF and move them straight into the VAT record, without retyping.

Commercial software makes sense when you need more, e.g. automatic downloading of invoices or integration with accounting. One thing works only through software integrated with the KSeF 2.0 API: invoices in the PEF structure from public procurement — you can’t send them through the Aplikacja Podatnika KSeF, the Aplikacja Mobilna KSeF or e-mikrofirma.

Frequently asked questions

Does a VAT-exempt JDG have to use KSeF too?

Yes. The obligation applies to active and exempt taxpayers who issue an invoice — on the same deadlines and with the same PLN 10,000 limit until the end of 2026. When an exempt taxpayer issues an invoice at all is explained in the article on VAT exemption.

Do I issue receipts in KSeF too?

No. KSeF covers invoices only.

Do I have to email the client an invoice from KSeF?

To a client with a Polish NIP — no, they'll find it in the system. To a consumer or a client abroad you pass it in an agreed way, e.g. as a PDF.

Can I give an accounting office access to my invoices?

Yes. You grant permissions in the Aplikacja Podatnika KSeF or in integrated software — to a single person or to the whole office.

Is an invoice issued outside KSeF despite the obligation invalid?

It doesn't lose its effect for VAT: the seller settles the tax, and the buyer can deduct VAT if the usual conditions are met. The issuer does, however, face a penalty for breaches from 1 January 2027.

One date in the calendar, access through Profil Zaufany and one test invoice while it’s still December — that’s all it takes for your first invoice in KSeF to be an ordinary invoice.
💜💙 Your BravoLisa Team

This article is for general information purposes only and does not constitute professional tax, legal, or accounting advice. Every situation is different — consult a qualified professional (tax adviser, accountant, or lawyer) for advice specific to your circumstances. BravoLisa does not accept liability for decisions made based on this information.

Last updated: September 2026. Rates and thresholds can change: always check them on biznes.gov.pl, podatki.gov.pl, zus.pl or with the relevant office.

Sources (8)

Verified on 30 September 2026

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2. KSeF — Poniżej 10 000 zł
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6. biznes.gov.pl — Jakie są rodzaje faktur
7. biznes.gov.pl — Jak wystawiać faktury VAT – podatnicy, którzy nie mają obowiązku korzystać z KSeF
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