KSeF is down — now what? offline24 mode, calmly explained

At the start of mandatory KSeF, in February 2026, some companies reported trouble logging in to the system, including through Profil Zaufany (the "Trusted Profile," Poland's government login). Issuing an invoice and logging in to KSeF are, however, two different things.

The lesson for any business is simple: government gateways will go down sometimes, and you still have to issue your invoice. That's exactly what offline24 mode is for — and despite the name, it isn't a "break-glass-in-emergency" tool. It's your everyday right to keep working without a connection. This article breaks it down.

"KSeF is down" vs "I can't log in" — not the same thing

Start with the distinction that saves you from a costly mistake. In practice "KSeF is down" is often a feeling that really means "I can't log in", for example via Profil Zaufany. Those are two different problems — and which special mode applies to you, and how long you have to upload, depends on what actually happened.

• Problem on your side (no internet, your software won't respond, KSeF is slow) → offline24 mode. You use it on your own initiative, without waiting for any announcement. The law does not require you to prove you had a connection issue.

• The Ministry of Finance announces unavailability or an outage in BIP MF (the Ministry's official public bulletin) → offline mode (planned downtime) or emergency mode (sudden outage). These are triggered by an MF announcement, not by you.

When the trouble is in logging in, and MF has announced no unavailability or outage in BIP, the right tool is offline24: your own decision to issue locally and upload the next day. Only a connection through a certificate frees you from logging in via Profil Zaufany.

Four modes for when "online" isn't working

Polish law foresees four ways of working outside online mode. They differ by cause, upload deadline, and how you hand the invoice to the buyer. Here's the cheat sheet:

The most common error is confusing "1 day" with "7 days." Remember: offline24 and planned unavailability = next business day; an MF-declared outage = 7 business days. The reverse mistake — waiting for MF to declare an outage when your router has simply died — just costs you time and sales. You're entitled to offline24 immediately.

MF documents the full procedures on its pages for offline24 mode and offline mode — KSeF unavailability.

offline24 mode, step by step

1. Issue the invoice in the FA(3) structure

Even with no connection to KSeF, the invoice must be an XML file matching the FA(3) schema (the structured e-invoice format in force since 1 February 2026). You can't send your customer a photo of a handwritten note — that's legal only during a total outage.

2. Mind the issue date

The issue date is the date you enter in field P_1 of the structure — not the date KSeF comes back and accepts the document. The invoice has legal force from the moment you issue it.

3. Add the QR codes

An invoice handed to the buyer outside KSeF (before it gets a KSeF number) carries two QR codes: the first (CODE I, "OFFLINE") gives access to the invoice in KSeF and lets the buyer verify its data (the link contains the seller's NIP, the issue date and the SHA-256 hash of the file, with no invoice number or amounts); the second ("CERTYFIKAT") confirms the issuer's identity. To generate the second one you need a KSeF certificate of the Offline type, which is separate from the login (Authentication) certificate; Biurko can order both. You need it before the connection drops, because you won't be able to get it issued once it's down. Without it Biurko issues the offline invoice with one code (CODE I) and a warning.

4. Deliver the invoice to the buyer — depending on who they are

• A domestic Polish VAT payer with a NIP (tax ID) receives the invoice through KSeF — formally only once it has a KSeF number.

• A foreign buyer, a consumer, or a buyer with no NIP (Article 106gb) receives the invoice through an agreed channel (email, portal). The receipt date is the actual date they receive it.

5. Upload to KSeF by the next business day at the latest

Once uploaded, the invoice gets its KSeF number — and that number is what matters for tax purposes. You can only issue a correction to an offline24 invoice after the original has been uploaded and assigned a number. The order is fixed: original → KSeF → number → correction.

Common traps

From talking to business owners and from how offline handling plays out in practice, a few mistakes recur:

1. Waiting for an MF announcement when it's your own internet that failed. Don't wait — switch to offline24 yourself.

2. No Offline certificate. Without it the second QR code (CODE II) is not produced, and an offline invoice handed to the buyer outside KSeF should carry both codes. Order the certificate ahead of time.

3. Paper instead of FA(3). A plain PDF or printout instead of the FA(3) structure is allowed only during a total outage.

4. Mixing up the 1-day and 7-day deadlines. Getting it wrong risks a penalty under Article 106ni — under the current act from 2027.

5. Issuing a correction before uploading the original. Without the original's KSeF number, you can't correct it.

6. A missing KSeF number for an offline invoice in JPK_V7. An offline invoice that received its KSeF number after the return was filed has to be included in a correction — make sure the upload happens before you close the period.

Under the current act, penalties under Article 106ni of the VAT Act (up to 100% of the invoice's VAT) apply from 1 January 2027. On 16 September 2026 the Ministry of Finance announced it will move them to 1 January 2028; that is a bill not yet passed, and it moves only the penalties, not the obligation to use KSeF, so build the habits now.

How Biurko handles offline24 for you

All of this sounds complex enough that it's easy to slip up under pressure. So at Biurko we turned it into a process that runs on its own:

• Automatic outage detection. When the KSeF gateway returns three errors within 60 seconds, Biurko switches new submissions into offline24 mode, instead of hammering a gateway that's already down. Every 5 minutes we also read the Ministry notices (the "Latarnia" feed) and pick the mode and the deadline accordingly.

• A compliant document, generated for you. The invoice is produced as validated FA(3) XML, with a QR code (CODE I) on its visualisation and, if the company has an Offline certificate, CODE II as well; the PDF shows the upload deadline.

• Deadline tracking. If the deadline passes and the invoice still hasn't reached KSeF, Biurko marks it "Needs review" and sends a notification; it does not resubmit an overdue invoice by itself. It does not warn you before the deadline runs out.

• Automatic resubmission on recovery. When KSeF comes back, queued invoices whose deadline has not passed are uploaded automatically every 5 minutes — no clicking through them one by one.

• For permanent work, a certificate, not Profil Zaufany. A session through Profil Zaufany does not renew itself: when it ends, you sign the XML again. For permanent, automatic work, order a KSeF certificate in Biurko (after the first connection through Profil Zaufany) and use it to connect. Biurko also monitors your certificate's validity: it warns you on screen 30 days before it expires and sends notifications 7, 3 and 1 day before and on the day it expires.

Checklist for a KSeF outage

• Order your KSeF certificate of the Offline type now (Biurko can order it from the Ministry) and don't wait for the connection to fail.

• Confirm your software issues offline invoices in FA(3) with both QR codes. To practise without legal effect, use the Biurko demo (demo.biurko.io, 7-day access, the KSeF demo environment). An account on app.biurko.io sends invoices to production KSeF, so every invoice you send there is real.

• Agree a delivery channel for offline invoices with key buyers (email, portal) so there's no dispute over the receipt date.

• Memorise the deadlines: offline24 and planned unavailability = next business day; an MF outage = 7 business days.

• Bookmark a way to check KSeF status, so you know whether it's the system or your own connection.

• Assign someone in your company to own the next-day upload of offline invoices.

Wrap-up

offline24 isn't a doomsday mode — it's your everyday safety net for when the network or the government gateway refuses to cooperate. You issue the invoice in FA(3), add the QR codes, deliver it to the buyer, and upload it to KSeF by the next business day at the latest. The rest is discipline and a good tool.

Biurko takes that discipline off your plate: it detects the outage, switches modes, flags invoices past the deadline, and uploads the rest once KSeF returns. Want to see it on your own invoices? Create an account: every new company gets 14 days of the TEAM plan without a card, then moves to the free FREE plan. To practise without legal effect, use the Biurko demo (demo.biurko.io, 7-day access, the KSeF demo environment).

FAQ

Can I issue invoices when KSeF is down? Yes. Use offline24 mode (when the problem is on your side) or offline/emergency mode if MF announces unavailability or an outage in BIP. You issue the invoice in the FA(3) structure, add the QR codes, and upload it to KSeF within the applicable deadline.

How long do I have to upload an offline24 invoice? By the end of the next business day after the issue date, at the latest. That's a shorter window than emergency mode (7 business days), which is why people confuse them — offline24 is always the next business day.

How is offline24 different from emergency mode? You trigger offline24 yourself when you have no internet or your software fails — no announcement needed. Emergency mode applies only once the Ministry of Finance declares a KSeF outage in BIP, and it gives you 7 business days to upload instead of one.

What is a KSeF Offline certificate? It is the certificate you use to sign the second QR code on an offline invoice ("CERTYFIKAT"), confirming your identity as the issuer. It is separate from the login (Authentication) certificate; Biurko can order both from the Ministry. Without it Biurko issues the offline invoice with one code (CODE I) and a warning.

Are there penalties for a late offline invoice? Under the current act, penalties under Article 106ni of the VAT Act (up to 100% of the invoice's VAT) apply from 1 January 2027. On 16 September 2026 the Ministry of Finance announced it will move them to 1 January 2028; that is a bill not yet passed, and it moves only the penalties, not the obligation to upload the invoice on time.