KSeF for micro-businesses: what to prepare before 1 January 2027

If your company issues only a few invoices, in 2026 it could use an exception and avoid sending them to the National e-Invoicing System (KSeF). That exception only applies until 31 December 2026. From 1 January 2027, KSeF will be mandatory also for businesses that have so far stayed within the limit of 10,000 PLN per month.

Below you will find an explanation of who this deadline applies to, how to calculate the limit, and what is worth preparing before the end of the year. This text describes the legal situation as of 8 November 2026 and is based primarily on materials from the Ministry of Finance.

Who does the 1 January 2027 deadline apply to?

In everyday language people talk about "micro-businesses", but the deadline is not determined by company size or the number of employees. What matters is the value of sales documented with invoices that would have to go through KSeF.

The Ministry of Finance schedule looks as follows:

• 1 February 2026 – the obligation to issue invoices in KSeF covered the largest entrepreneurs, and receiving invoices began to take place through this system.
• 1 April 2026 – the obligation to issue invoices covered the remaining entrepreneurs, except for businesses within the limit of 10,000 PLN per month.
• 1 January 2027 – the obligation will also cover businesses that were using that limit.

Being exempt from VAT does not exclude you from KSeF. The Ministry of Finance indicates that an invoice in KSeF is issued by every taxpayer required to issue it, both active and exempt. VAT-exempt taxpayers are also covered by the 10,000 PLN limit applicable in 2026.

How does the 10,000 PLN limit work?

The limit applies to the total monthly value of sales including tax, that is gross amounts. You only count in it invoices that, as a rule, should be issued in KSeF.

You do not count towards the limit, among others:

• invoices issued using a cash register,
• receipts up to 450 PLN with the buyer's tax ID (NIP), treated as simplified invoices,
• consumer invoices, that is those issued to private individuals,
• sales to private individuals documented solely by a cash register.

The exclusions regarding the cash register and receipts with a NIP apply only until 31 December 2026. From 1 January 2027, a receipt with a NIP up to 450 PLN stops being a simplified invoice, and an invoice for a company covering a sale recorded on a cash register must be issued in KSeF. Invoices for private individuals are still not covered by the obligation. If you use a cash register and also sell to companies, this change affects you directly.

You assign an invoice to the month in which it was issued, not to the month of the sale.

What happens once the limit is exceeded?

The obligation arises from the invoice that exceeded the limit. That invoice and all subsequent ones must go through KSeF. A drop in sales in the following month changes nothing, because you cannot return to invoicing outside the system.

Example: in October you issue three invoices of 4,000 PLN gross to companies. After two invoices the total is 8,000 PLN, so you are within the limit. The third raises it to 12,000 PLN, which is why you issue the third invoice and all subsequent ones in KSeF.

The amount of 10,000 PLN itself still fits within the limit. Article 145m of the VAT Act refers to sales "less than or equal to" 10,000 PLN, so the obligation arises only once the total exceeds this amount, even by a single grosz.

If the limit was exceeded earlier in 2026, the 1 January 2027 deadline does not apply to you, because the obligation already exists. It is worth checking this first.

Receiving invoices: this is not an obligation only from 2027

The deferral concerns only the issuing of invoices. As the Ministry of Finance states, receiving invoices takes place through KSeF from 1 February 2026, and the later deadline for issuing does not change this.

In practice this means three things:

• An invoice is considered received on the day it is assigned a KSeF number (Article 106na(3) of the VAT Act), even when no one in your company has opened it yet.
• KSeF does not send notifications about new invoices, so you have to check yourself whether anything has arrived.
• Email is a supplementary channel. The seller is not required to additionally send the invoice outside the system, so a message with a PDF may simply not arrive.

If invoices have so far been arriving by email, it is worth changing that habit and regularly checking KSeF, or entrusting it to an accountant. Purchase invoices directly affect costs and tax settlements, so it is easy to overlook a document that the system will not remind you about on its own.

What to prepare before 1 January 2027: a checklist

1. Check your situation

Review the invoices issued from 1 April 2026. Check whether the limit has not already been exceeded and which documents are actually subject to KSeF. If you sell only to private individuals, consumer invoices are not covered by the obligation, but you still receive purchase invoices from companies through KSeF.

2. Choose how you will issue invoices

You do not have to buy software. The Ministry of Finance provides free of charge the KSeF Taxpayer Application and a Mobile Application. The e-Tax Office also offers the e-mikrofirma application, in which you can issue an invoice in KSeF and transfer received invoices to your VAT records without re-entering the data. With a small number of invoices, this may be enough.

Commercial software is useful when you want to combine invoicing with accounting or issue invoices with attachments, since the Ministry's free applications do not support them. The software alone is not enough: the intention to issue invoices with an attachment must be reported in advance to the Head of the National Revenue Administration (KAS), exclusively via the e-Tax Office. If your software previously used a KSeF token, remember that tokens from KSeF 1.0 do not work in KSeF 2.0.

3. Check that you can log in

Before your first invoice, make sure you can access the system. The Ministry lists, among others, logging in via the Trusted Profile, the mObywatel app, electronic banking, an e-ID card, and a qualified signature. The available methods depend on the legal form of your company.

If you run a sole proprietorship, you log in directly, for example with the Trusted Profile or via mObywatel. KSeF automatically grants you owner permissions, so a ZAW-FA notification is not needed.

A company without a qualified seal files a ZAW-FA notification, in which it designates one individual with the broadest permissions. That person can later grant permissions to further people electronically. ZAW-FA can be filed on paper or electronically via the e-Tax Office or e-Delivery (not via ePUAP). A version sent by post requires time for delivery and data entry, so it is not worth leaving it to the last days of December.

While you are at it, download the KSeF certificate for offline work. The VAT Act (Article 106nda(7)) requires the taxpayer to download from KSeF a certificate that confirms the identity of the issuer of an invoice issued outside the system. According to the Ministry of Finance, marking an invoice with a QR code in offline24 mode, during system unavailability and during an outage requires a type 2 (offline) KSeF certificate. The certificate is valid for a maximum of 2 years. If you download it in advance, in the event of problems with the system you will not have to suspend invoicing.

4. Grant permissions to your accountant

If you use an accounting office, agree on who will issue invoices and who will only receive and record them. A permission can be granted to the entire office with the option that the office may pass it on to its employees. A third party issuing an invoice on your behalf must have the appropriate permission.

5. Set the rules for working with invoices

Decide who checks new purchase invoices and how often, who approves them for payment, and where they are passed on for recording. Also agree with your contractors whether you want to additionally receive a PDF from them as a convenient supplement, remembering that this is not their obligation.

6. Prepare payments: the KSeF number in the transfer

From 1 January 2027, the way you pay for invoices also changes. Article 108g of the VAT Act imposes an obligation to state in the transfer the invoice's KSeF number, and when paying for several invoices at once, a collective identifier assigned by KSeF. The provision applies to payments made from 1 January 2027 (Article 17 of the Act of 16 June 2023 as worded in 2025). From the same day, the KSeF number also appears in the transfer message under the split payment mechanism (Article 108a).

The obligation concerns a situation where an active VAT taxpayer pays by transfer to another active VAT taxpayer. If you are VAT-exempt or you pay a VAT-exempt seller, the provision does not cover you. It also does not apply to card or cash payments. The seller's status is checked in the register of VAT taxpayers (the "white list") as at the date of payment.

In practice, before January it is worth checking where in your online banking and your invoicing software the invoice's KSeF number is shown, and agreeing with your accountant who prepares the transfers.

7. Practise an invoice and a correction

Do not wait until January for your first attempt. The Ministry of Finance provides a test version of the KSeF Taxpayer Application, and many commercial programs have their own test mode. Issue a trial invoice and a correction, and at the same time check that you are entering the buyer's NIP and the basic invoice data correctly. The Ministry recommends not using real company data in the test environment.

Errors and outages: what is worth knowing in advance

An invoice accepted by KSeF cannot be edited. You correct a mistake with a correcting invoice. If you get the buyer wrong, the Ministry indicates issuing a correction to zero and then a new invoice with the correct NIP.

It is different when the system rejects the file. A structured invoice comes into existence only after it is sent to KSeF (Article 106na(1) of the VAT Act), so a rejected file is not an invoice and there is nothing to correct. You have to send a new, correct file.

The VAT Act (Articles 106nda, 106nf and 106nh) also provides for working in emergency modes:

• offline24 – you send the invoice to KSeF without delay, no later than the next working day after issuing it,
• system unavailability (for example maintenance work, which the Ministry of Finance announces in the Public Information Bulletin) – no later than the next working day after it ends,
• KSeF outage – within 7 working days of its end.

Separate rules apply to a total breakdown, that is an extraordinary situation that the Ministry of Finance announces in a special notice. Invoices issued during that time do not have to be sent to KSeF afterwards.

What penalties are there for not using KSeF?

Administrative penalties. In 2026, no administrative penalties are applied for KSeF-related violations. Under the regulations currently in force, the penalties under Article 106ni of the VAT Act are to apply to violations from 1 January 2027:

• for issuing an invoice outside KSeF when it was required – up to 100% of the VAT amount on the invoice,
• for an invoice without a VAT amount – up to 18.7% of the total amount due.

These are maximum values, not rates applied automatically for every error.

Fiscal criminal liability. Regardless of the year, merely issuing an invoice outside KSeF, or late sending of an invoice issued in offline24 mode, during unavailability or during a system outage, does not carry fiscal criminal liability. Article 106ni(4) of the VAT Act excludes proceedings under the Fiscal Penal Code in these cases, and this provision is not covered by the deferral. However, Article 62 of the Fiscal Penal Code still applies, providing for a fine for not issuing an invoice at all or for issuing it unreliably.

On 20 October 2026, the government submitted to the Sejm a bill postponing the entry into force of the penalty provisions (Article 106ni(1)–(3) and (5)–(7)) to 1 January 2028 (paper no. 3245). The Sejm passed the act on 6 November 2026. It now goes to the Senate, which has 30 days for this (Article 121 of the Constitution). If it introduces amendments, the act returns to the Sejm, and only then goes to the President, who has 21 days to sign it (Article 122 of the Constitution). The act is to enter into force on 31 December 2026, so it must be published in the Journal of Laws before that date. If these deadlines are used in full, this may not happen in time. Until it does, the 1 January 2027 deadline applies, which is why it is worth following its further progress. Most importantly, the act does not postpone the obligation to use KSeF itself. Even if the penalties are deferred, from 1 January 2027 invoices must be issued in the system.

Frequently asked questions

Do I have to use KSeF if I issue only one invoice a month?

Yes, if it is an invoice covered by the obligation, for example for another company. From 1 January 2027 there will no longer be a limit allowing it to be issued outside the system.

Do invoices for private individuals also have to be issued in KSeF?

No. Consumer invoices are not covered by mandatory KSeF. They can be issued in the system voluntarily.

How do I pass an invoice to a contractor from abroad?

A foreign buyer will not log in to KSeF to download the invoice. The seller passes it on in an agreed way, for example as a PDF with a QR code.

How long are invoices stored in KSeF?

For 10 years, counting from the end of the year in which they were issued.

Where can I check official information?

On the ksef.podatki.gov.pl website. Particularly useful are the section on invoices up to 10,000 PLN per month and the questions and answers about KSeF 2.0.

KSeF at VirtOffice

At VirtOffice we support KSeF. If you buy our services, we send the purchase invoice to KSeF automatically.

If you do not want to keep track of invoices, declarations and deadlines yourself, check out our online accounting. The service is handled by the accountants of Mobilni Księgowi, and the net prices are:

• Lump-sum tax (ryczałt) – from 125 PLN per month,
• Revenue and expense ledger (KPiR) – from 145 PLN per month,
• Full accounting books – from 395 PLN per month.

Prices do not include VAT. Not sure which package is right for you? Read how to choose accounting for your company, and check the most common accounting mistakes of beginner entrepreneurs.

Do you want to get KSeF in order in your company before the end of the year? Book a consultation or choose an accounting package.

This article is for information purposes only and does not constitute legal or tax advice. The regulations on KSeF may change, so before making a decision check their current wording or consult your situation with an accountant.