Which KSeF software should you choose in 2026?

Search for a KSeF software ranking and you will find a dozen lists where the top spot belongs to whoever pays the highest referral fee. The order changes from site to site, the reasoning does not. Those are not rankings, they are rate cards.

This piece differs on two counts. There is no single winner, because a company issuing three invoices a month and an accounting firm serving eighty clients need entirely different tools. And I am the founder of one of the products compared here, which I would rather state up front than pretend to be a neutral reviewer.

Below are seven company profiles, a specific recommendation for each, and a section on when Biurko is the wrong choice.

In short

• KSeF (Poland's national e-invoicing system) support is no longer a differentiator. Every serious vendor has it, so comparing that column tells you nothing.

• The real differences are the authentication method, offline mode handling, error readability, multi-entity work, and export to your bookkeeping system.

• The Ministry of Finance's free tools are genuinely sufficient at a few invoices a month and should not be dismissed.

• Under the current act, penalties under Article 106ni of the VAT Act 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.

Why most KSeF software rankings are useless

A typical comparison table has three columns: price, "KSeF support: yes", mobile app. The problem is that since 1 April 2026 mandatory KSeF invoicing covers practically every VAT payer (the smallest follow from 1 January 2027), so that middle column reads the same everywhere. It is a condition of doing business, not an advantage.

The second flaw is comparing incomparable things. A simple invoicing tool at 10 PLN, a document-workflow platform for accounting firms, and an ERP with warehouse management all land in one table and get scored out of ten. The score is meaningless because each solves a different problem.

So instead of a ranked list, this article sorts by the situation you are actually in.

What actually separates KSeF software in 2026

If you compare anything, compare these seven things.

KSeF authentication method. Certificate, token, or Profil Zaufany (Poland's national digital identity). The KSeF certificate is architecturally the most stable option: it stays yours and works across multiple programs. Under the current rules KSeF tokens expire on 31 December 2026. At consultations on 9 June 2026 the Ministry of Finance proposed keeping them, but no regulation has been adopted yet. Software that supports tokens only ties you to regulatory uncertainty.

Offline modes. Offline24 mode lets you issue an invoice without a KSeF connection and submit it no later than the next business day. If you hand that invoice to the buyer before it reaches the system, the visualisation must carry two QR codes: KOD I (labelled OFFLINE) and KOD II (labelled CERTYFIKAT), and the second requires a KSeF certificate of the Offline type. Check whether your software generates both, because several tools on the market print only the first.

Error readability. KSeF returns numeric codes. The difference between software that shows "error 21115" and software that explains "a certificate issued before 1 February 2026 does not work in KSeF 2.0, generate a new one" is the difference between an hour and five minutes.

Multi-entity work. If you run two companies or serve clients, what matters is switching entities without logging out, roles and permissions, and separate KSeF connections per NIP (Polish tax identification number).

Inbound invoice handling. Automatic retrieval of purchase documents from KSeF, cost categorisation, and flagging of entries that need a human check. This is the half of the obligation rankings ignore, because it is harder to measure.

Export to bookkeeping. If your accountant works in Comarch ERP Optima, Symfonia, enova365, or InsERT, software without an export path to those systems means manual re-keying.

Pricing model. Per user, per entity, per document, or per credit. With one company the difference is cosmetic. With twenty it determines the invoice.

The ranking by need

Prices are net, indicative, as of September 2026 (Biurko: per its price list of 8 October 2026). Always verify with the vendor, because they change several times a year.

1. A few invoices a month, no budget: the Ministry of Finance tools

The KSeF 2.0 Taxpayer Application handles issuing, receiving, and browsing invoices in the FA(3) schema, VAT RR farmer invoices, subordinate units, and permission management. There is also a KSeF 2.0 mobile app and e-mikrofirma inside the e-Tax Office for sole proprietors.

This is the reference implementation of the regulations, free of charge. At two invoices a month to one counterparty there is no reason to pay for anything else. The limits show up at scale: no convenient counterparty database, no cost ledger, no team work.

2. A sole proprietor who wants invoicing and an accountant in one place: inFakt

Invoicing from roughly 5 PLN a month on annual billing, self-service bookkeeping around 50 PLN, a dedicated accountant from roughly 190 PLN. The strengths are cost OCR, a solid mobile app, and the fact that a human files your annual return.

This is the best fit for a typical one-person service business that wants bookkeeping off its plate inside one ecosystem. Biurko deliberately does not compete here.

3. A small company doing its own bookkeeping: wFirma

Modular pricing: invoicing with CRM 19 PLN, online bookkeeping 49 PLN, full accounting 99 PLN, HR and payroll 49 PLN, warehouse 30 PLN. There is a separate pricing page for accounting firms billed per client.

It makes sense when you need bookkeeping, stock, and payroll in one system and accept stacking modules. For invoicing alone, 19 PLN is expensive next to the free alternatives.

4. Foreign clients and e-commerce: Fakturownia

A Micro plan at 0 PLN capped at three invoices a month, paid plans from roughly 12 PLN. The differentiators are multilingual invoices and integrations with online stores. If you sell through Shoper, Shopify, or Allegro and invoice in several languages, this is the right direction.

5. The cheapest sensible paid plan: FakturaXL

The free tier covers around ten documents a month with KSeF support and no time limit. The full plan with the simplified tax ledger and JPK files costs roughly 10 PLN. The interface is dated and the mobile app is weak, but the price-to-function ratio is hard to beat, and it exports to Rachmistrz, Rewizor, and Optima.

6. An accounting firm with paper document flow: SaldeoSMART

This is not invoicing software. It is an automation layer between the client and the accounting system, integrating with more than forty of them including Comarch ERP Optima, enova365, Symfonia, and InsERT. Billing combines a functional package with a credit pool, so pricing is quoted individually.

If your clients still send scans and phone photos, OCR is worth more to you than any KSeF module.

7. Several entities, a team, and three interface languages: Biurko

This is where I stop being impartial, so here are specifics instead of adjectives. Biurko offers FREE (0 PLN with no time limit: one company, invoices and KSeF submissions without a limit), SOLO at 29 PLN, PRO at 59 PLN, TEAM at 99 PLN (five users and up to five companies) and SCALE at 199 PLN (no limit on people or companies), all net per month. Each company has its own plan, and annual billing is 20 percent cheaper. Every new company gets 14 days of the TEAM plan without a card, then moves to the free FREE plan.

We built it around four things: certificate or Profil Zaufany authentication instead of tokens, a multi-company panel with roles and permissions, KSeF error messages translated into plain language, and an interface in Polish, English, and Ukrainian. It also covers the full FA(3) and FA_RR schemas, purchase invoice import with review flags, VAT registers and JPK_V7 files, and AI access (an MCP server, from the SOLO plan) if you want to work with invoices through an AI assistant.

When Biurko is the wrong choice

We have no payroll, no warehouse, no double-entry accounting, no KPiR and no annual PIT return. If you want one system to run the whole company, wFirma or an ERP will serve you better.

We have no bulk OCR for paper invoices (AI reads purchase invoices from a PDF or a scan, 1 credit per page, up to 30 pages). An accounting firm whose clients still arrive with a bag of receipts needs SaldeoSMART, not us.

We have no native mobile app (there is a PWA with push notifications) and no PSD2 bank integration. If you invoice from your phone in the field, pick inFakt or Fakturownia.

We do not provide an accountant. A single sole proprietorship that wants to hand bookkeeping to a person should go to inFakt.

We are also a young product with a small team. If your criterion is fifteen years on the market and a three-shift support desk, that is not us.

Checklist before you decide

1. Confirm the software supports KSeF certificate authentication, not tokens alone.

2. Issue a test invoice in offline24 mode and count the QR codes on the visualisation. There should be two (KOD I and KOD II), provided you hold a KSeF certificate of the Offline type.

3. Trigger an error deliberately, for example a wrong buyer NIP, and see what the software shows you.

4. Import a month of purchase invoices from KSeF and count how many entries need manual correction.

5. Ask your accountant what format they want the data in, then verify the export.

6. Calculate the annual cost for your number of entities and users, not the starter plan price.

7. Check that you can export your data if you decide to leave.

Summary

There is no best KSeF software, only software best matched to your invoice volume, entity count, and bookkeeping arrangement. Under the current act, penalties under Article 106ni of the VAT Act 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. Use that window to run two or three tools against real documents.

If you run several entities, work as a team, or need a panel in Polish, English, and Ukrainian, create a free Biurko account. 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. The FREE plan has no expiry date.

FAQ

Which KSeF software is best in 2026? There is no single answer. At a few invoices a month the free Taxpayer Application is enough. A sole proprietor with an accountant picks inFakt, a company with a warehouse picks wFirma, an accounting firm with paper flow picks SaldeoSMART. Document volume, entity count, and your bookkeeping arrangement decide.

Is free KSeF software enough? For a micro business issuing a handful of invoices a month, yes. The Ministry of Finance tools cover the full cycle: issuing, receiving, corrections, UPO confirmations, and permissions. The limits are ergonomics at scale plus the absence of a cost ledger and team access.

Do I have to change software before 2027? If your current software submits to KSeF correctly and supports offline24, no. Two things are worth verifying: certificate authentication and the QR codes on offline invoices, because under the current act penalties under Article 106ni of the VAT Act apply from 1 January 2027 (the Ministry of Finance has announced it will move them to 1 January 2028; that is a bill not yet passed).

What KSeF software should an accounting firm use? It depends where the documents come from. If clients bring paper, you need OCR, so SaldeoSMART or a similar layer above your accounting system. If documents already sit in KSeF, a multi-company panel with roles and an export path to your bookkeeping software matter more.

How much does KSeF software cost? From 0 PLN to a few hundred a month. Free plans usually cap at three to ten documents. Simple invoicing tools run 10 to 20 PLN net, self-service bookkeeping 50 to 100 PLN, and an accountant-included service from roughly 190 PLN. Accounting firm solutions are priced per client or per document.