How to use the KSeF test environment

The test environment of KSeF (Krajowy System e-Faktur, Poland's National e-Invoicing System) has its own version of the Taxpayer Application (Aplikacja Podatnika) at ap-test.ksef.mf.gov.pl/web/. Documents you send there are not invoices and have no legal effect, and you may enter only fictitious data.

Status as of 12 November 2026.

MF: Aplikacja Podatnika KSeF 2.0 KSeF 2.0 Manual, Part II, ch. 3.2.1

How do TEST, DEMO and production differ?

KSeF 2.0 has three public environments. TEST is for testing integrations and gets new system versions first. DEMO (the pre-production environment) is configured like production and is for the final check of an integration. Production (PROD) is where you issue and receive invoices with full legal effect.

MF (the Ministry of Finance) gives the addresses of the test and pre-production Taxpayer Application on the pages for each version. Older guides still mention web2te-ksef.mf.gov.pl, which no longer works.

TEST also accepts the older FA(2) schema, while DEMO and production no longer do. A file accepted in TEST may still fail in production.

CIRFMF: KSeF environments

What can you enter in the test environment?

Enter only made-up data. The MF documentation forbids sending production invoices and real company data to TEST and DEMO, and tells you to use random NIP numbers (Polish tax IDs) for testing.

The reason is practical: TEST accepts self-signed certificates, so many people can log in in the context of the same company. Data entered in TEST is not isolated and other users can see it. So don't enter a real client or their address. MF says data in the test and pre-production Taxpayer Application is deleted periodically, but gives no schedule.

CIRFMF: KSeF environments, note MF: Aplikacja Podatnika KSeF 2.0, test version

Other ways TEST differs from production:

• Maintenance windows. Since 1 October 2025, recurring maintenance may take place in the test environments between 16:00 and 18:00, and disruptions may occur then. MF announces additional work in its technical notices (for example the notices of 17 and 22 June 2026).
• UPO with a suffix. In a UPO (Urzędowe Poświadczenie Odbioru, the official confirmation of receipt) from TEST, the receiving party reads "Ministerstwo Finansów - środowisko testowe (TE)" (Ministry of Finance, test environment), and from DEMO "Ministerstwo Finansów - środowisko przedprodukcyjne (TR)" (pre-production environment). In production it is just "Ministerstwo Finansów".
• QR codes point to a test address. The QR code on a test invoice leads to qr-test.ksef.mf.gov.pl, not to verification in production (qr.ksef.mf.gov.pl).

CIRFMF: API changelog, 2.0.0 RC6.0 CIRFMF: QR codes KSeF 2.0 Manual, Part II, ch. 3.2.3

How do you log in to the test environment?

You don't need a qualified certificate for the test Taxpayer Application. On the login screen, choose "Zaloguj uwierzytelnieniem testowym" (log in with test authentication), enter the context (e.g. the company's NIP, the Polish tax ID) and type a NIP or PESEL (Polish personal ID number). The server signs the request with a test certificate. You can't log in to TEST with Profil Zaufany (the Polish government e-ID); that option works only in DEMO and production. TEST accepts a qualified certificate, but MF advises against using signatures with real data there. We cover logging in to production in our guide to KSeF login.

Only TEST accepts a self-generated certificate instead of a qualified one. For API connections, one tool that creates such a certificate is KSeF.Client.Tests.CertTestApp from the official C# library (more on it below). It is a developer tool.

DEMO requires real login credentials and real permissions, just like production. You log in there with e.g. Profil Zaufany, in the context of a NIP that matches the register of company owners. That is why the MF manual calls DEMO not publicly available, even though the API documentation lists it among the public environments. Permissions and certificates granted in the production Certificates and Permissions Module (MCU) are not available in DEMO, and nothing you do in DEMO changes anything in production.

MF: authentication guide for the test Aplikacja Podatnika KSeF 2.0 MF: Aplikacja Podatnika KSeF 2.0, pre-production version (Demo) CIRFMF: authentication KSeF 2.0 Manual, Part II, ch. 3.2.2

How do you practise issuing an invoice?

1. Open ap-test.ksef.mf.gov.pl/web/ and check the address in your browser: it should contain "ap-test". Log in with test authentication and a made-up NIP.
2. Issue an invoice with a made-up buyer and amount. We walk through the form step by step in the guide to your first invoice in the Taxpayer Application.
3. Download the UPO and check for the suffix "środowisko testowe (TE)" (test environment).

If you invoice from software rather than the browser, switch it to the test environment and send a test invoice from it. Once you have an XML file, you can check it in the validator before sending, against the FA(3) schema that production requires.

How do you connect software to the test environment API?

Marek is connecting an ERP system to KSeF. The base API URL in TEST is https://api-test.ksef.mf.gov.pl/v2 (path /v2, not /api/v2). The official MF libraries connect to DEMO and production through the hosts api-demo.ksef.mf.gov.pl and api.ksef.mf.gov.pl with the same /v2/... paths. URLs returned by the API always point to the environment that received the request.

You can download the TEST specification as openapi.json, and the interactive documentation is at docs/v2/index.html.

CIRFMF: open-api.json (2.9.0)

How do you set up test data?

The /testdata/* endpoints prepare data for test scenarios:

• POST /testdata/person: a natural person with owner permissions. With isBailiff: false this corresponds to a JDG (jednoosobowa działalność gospodarcza, a Polish sole trader): the person logging in with a PESEL (Polish personal ID number) or NIP gets the Owner permission. With isBailiff: true, EnforcementOperations (bailiff) is added.
• POST /testdata/subject: a VAT group or a JST (local government unit) with subordinate units, followed by permissions via POST /testdata/permissions.
• POST /testdata/attachment and /revoke: enabling and disabling attachments.
• POST /testdata/context/block and unblock: a blocked context, where authentication fails with error 480.
• PUT /testdata/certificates/{serialNumber}: shortening a certificate's validity.
• The /testdata/limits/* and /testdata/rate-limits endpoints: changing limits, with no effect on production.

Some of them carry the note "Tylko na środowiskach testowych" (Only in test environments) in the specification. The documentation doesn't define whether that includes DEMO. POST /testdata/rate-limits/production works only in TEST.

CIRFMF: test data, scenarios

Which limits apply in TEST?

The MF documentation contradicts itself. The limits page says limits in TEST are ten times higher than in production, while the changelog for version 2.5.0 says they were aligned with production. In DEMO the limits are the same as in production. You can read the current values from GET /rate-limits.

CIRFMF: API limits

What else works in the test environments?

• The X-Test-System-Warning header forces a system warning in the response.
• The X-KSeF-Feature: subject-identifier-validation header turns on checking of NIP numbers and internal identifiers on invoices (the documentation doesn't specify whether it also works in DEMO).
• New API versions reach TEST first, then DEMO and production. Version 2.9.0 went live in TEST and DEMO on 13 October 2026, and in production on 15 October.

MF maintains two open source libraries: ksef-client-csharp (C#) and ksef-client-java (Java). You select the environment in their configuration, and the sample apps in both repositories connect to TEST by default. CertTestApp from the C# library requires the .NET 10 SDK and generates a random NIP by default.

CIRFMF: API changelog CIRFMF: test certificates and XAdES signatures

Once a test invoice goes through and its UPO carries the "(TE)" suffix, issue the real invoice in the production application at ap.ksef.mf.gov.pl.