Does a sole proprietor in Poland need to use KSeF in 2026?

KSeF for sole proprietors comes with a deadline. If you run a one-person business in Poland (a JDG, jednoosobowa działalność gospodarcza), someone has probably told you: "You're fine until the end of the year, you're under the 10,000 zloty limit." That is partly true. The exemption expires on 31 December 2026, and it stops protecting you from the very invoice that pushes a month over the limit.

From 1 January 2027, using KSeF (Krajowy System e-Faktur, Poland's national e-invoicing system) becomes mandatory for all businesses. The Ministry of Finance said so on 16 September 2026 <!-- TODO: replace with the original MF announcement on gov.pl -->, because the transitional periods end on 31 December 2026.

This guide covers who is exempt, how the limit is calculated, what stays outside KSeF for good, and where the penalty rules really stand. Legal position as of 15 October 2026. I'm the founder of a Polish invoicing SaaS, not an accountant, so check your own case with one.

KSeF for sole proprietors: the short answer

Yes, from 1 January 2027 nearly every sole proprietor who invoices other businesses has to do it through KSeF. Until the end of 2026, the only ones who can stay outside are those whose invoiced sales do not exceed PLN 10,000 gross per month.

Receiving invoices is a separate duty. Purchase invoices have to be received in KSeF from 1 February 2026, regardless of the limit. In practice, a supplier can issue an invoice to you in KSeF without emailing it, so you need to check the system.

Date What changes Who 1 Feb 2026 Receiving invoices in KSeF; issuing in KSeF Receiving: everyone. Issuing: companies with sales above PLN 200 million in 2024 1 Apr 2026 Issuing invoices in KSeF Everyone else, including sole proprietors above the PLN 10,000 limit 31 Dec 2026 The "up to PLN 10,000" exemption ends The smallest taxpayers 1 Jan 2027 Full obligation All businesses

Who is exempt from KSeF until the end of 2026

Until 31 December 2026 you may issue paper or ordinary electronic invoices if their total gross value in a given month stays at or below PLN 10,000. The rules, per the Ministry of Finance:

• The limit is gross and based on the invoice issue date.

• Only invoices that must go through KSeF count, meaning B2B sales. Cash-register invoices, receipts with a buyer's tax ID (NIP) up to PLN 450, and consumer invoices do not.

• Once you exceed the limit, the invoice that crossed it and every later one must be issued in KSeF, even in months when your sales drop again.

Example: a freelance developer invoicing Polish companies.

April:  PLN 4,500 + 3,200 = 7,700          -> outside KSeF
May:    PLN 6,000 + 3,500 = 9,500          -> outside KSeF
        + PLN 1,800 (third invoice) = 11,300
                                            -> this invoice goes into KSeF
June–December: every B2B invoice in KSeF, even in a PLN 2,000 month

The Ministry's own example: a florist issuing three invoices a month of PLN 1,500–2,500 can invoice outside KSeF through 2026 and must use it from 1 January 2027.

Being VAT-exempt does not make you KSeF-exempt

A common assumption is "I'm not a VAT payer, so KSeF isn't for me." According to the Ministry's Q&A, the obligation applies to any taxpayer, VAT-registered or exempt, who has to issue an invoice. What matters is whether you issue an invoice, not your VAT status.

For VAT-exempt sales an invoice is issued on the buyer's request. If a company asks you for one, you issue it in KSeF unless you are still under the PLN 10,000 limit in 2026. If nobody asks, there is nothing to send.

What stays outside KSeF regardless of the limit

• Invoices to consumers (private individuals without a business) are excluded from KSeF.

• VAT RR invoices (issued when buying from flat-rate farmers) are not part of mandatory KSeF.

• Cash registers and receipts with a NIP up to PLN 450 (or EUR 100) can replace an invoice outside KSeF until 31 December 2026. Per the Ministry, from 2027 an invoice for a till transaction with a business buyer has to be issued in KSeF.

If you are a foreign company working with Polish sole proprietors

Two practical points. First, the invoice you receive from a Polish contractor will legally be a structured data file stored in KSeF; any PDF you get is only a visual copy, and it may not differ from the KSeF invoice. Your accounts payable team should match payments to KSeF records, not to emailed PDFs.

Second, the Ministry states that KSeF is not used to report purchases from foreign suppliers. The system concerns invoices issued by Polish taxpayers.

Penalties: what is law and what is only an announcement

Financial penalties for not using KSeF and for errors are set out in Article 106ni of the VAT Act. For 2026 there are no penalties. They were due to start on 1 January 2027.

On 16 September 2026 the Ministry announced it wants to postpone them to 31 December 2027, and on 23 September a draft law was published. This is not law yet: until it is passed, the earlier date formally stands. The Ministry also stresses that deferring penalties does not remove the duty to use KSeF, and the tax authority is expected to react to invoices issued outside the system.

According to published analyses, the maximum penalty is up to 100% of the VAT on an invoice issued outside KSeF. A later start date lowers the immediate risk, not the obligation.

Checklist for sole proprietors before 1 January 2027

1. Add up this month's gross B2B invoices (by issue date) and see how far you are from PLN 10,000.

2. Log in to the free KSeF Taxpayer Application and check whether suppliers are already invoicing you there.

3. Agree with your accountant who collects purchase invoices from KSeF, and how often.

4. Check that your invoicing software submits to KSeF and downloads the UPO (the official confirmation of receipt).

5. Start issuing in KSeF before January. There are no penalties in 2026, so this is the cheapest time to make your first mistakes.

6. Keep consumer and till sales separate from B2B invoicing.

Conclusion

A sole proprietor needs KSeF by 1 January 2027 at the latest. Until the end of 2026 the only protection is the PLN 10,000 gross monthly limit, and one breach switches it off for the rest of the year. If you are under the limit, you don't have to buy anything before December, but the later you start, the less time you have to test.

Biurko submits invoices to KSeF at the moment of issuing, receives purchase invoices and downloads the UPO, and the interface is available in English, Polish and Ukrainian. Try it free for 14 days at biurko.io and send your first invoice through KSeF before December turns into a rush.

FAQ

Does a VAT-exempt sole proprietor have to issue invoices in KSeF?

Yes, if they issue an invoice. The duty depends on whether an invoice is issued, not on VAT status. For VAT-exempt sales an invoice is normally issued on the buyer's request. Then it goes through KSeF, unless you are under the PLN 10,000 monthly limit until the end of 2026.

Until when can I issue invoices outside KSeF?

Until 31 December 2026, provided your monthly sales documented by invoices do not exceed PLN 10,000 gross. The invoice that crosses the limit already goes into KSeF. From 1 January 2027 the exemption ends and B2B invoices go through KSeF. Consumer invoices remain outside the system.

What happens if I exceed PLN 10,000 in one month?

The invoice that crosses the limit and all later invoices must be issued in KSeF. You cannot go back to invoicing outside the system, even if sales fall below PLN 10,000 in later months. The issue date of the invoice decides.

Will there be KSeF penalties from 1 January 2027?

Under current law, penalties were due to start on 1 January 2027. The Ministry of Finance announced a delay to 1 January 2028 and published a draft law, but it has to be passed first. The obligation to use KSeF from 2027 does not change.

Do invoices to private individuals go through KSeF?

No. Invoices to consumers, meaning private individuals without a business, are excluded from KSeF and do not count toward the PLN 10,000 limit. KSeF is used for invoices issued to businesses and other taxpayers. Such an invoice, if the customer asks for one, is issued outside the system under the usual rules.