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KSeF API: test scenario examples
Short answer
You accept a KSeF API integration on scenarios, because a single successful call does not confirm the invoice flow. Check a valid and a rejected document, an interrupted wait for the result, a retry without a duplicate operation and missing permissions. At Syntalith an automation costs from €3,000 net, and with 1,000 invoices a month at 3 minutes each it pays back in 2.0 months.
How we workDetails ↓
- 01Call30 minutes with an engineer, free
- 02PrototypeA working system on your process and data, free
- 03ImplementationTarget and fixed price in the contract; 50% at signing
- 04Acceptance50% once the agreed target is met
- net for the automation of one process, paid once
- from €3,000
- from signing the contract to acceptance
- 2–6 weeks
- free prototype on your cases
- €0
We belong to the OpenAI and Anthropic partner programmes and learn through their official courses. What this means ↓
Author: Syntalith · 3 min read
Statistics
KSeF in Poland: statistics 2026
2.0 mo.
payback of a €3,000 automation at 1,000 invoices a month: €1,745 of work today, €269 with checking and the model. Scenario.
1 February 2026
According to Poland's Ministry of Finance (2026), all companies in Poland receive invoices through KSeF from 1 February 2026.
87 million
According to Poland's Ministry of Finance (2026), KSeF took in over 87 million invoices in its first two months.
3 million
According to Poland's Ministry of Finance (2026), the busiest day so far was 3 March 2026, when over 3 million invoices reached KSeF.
70,000
According to Poland's Ministry of Finance (2026), the National Tax Information service answered over 70,000 emails about KSeF from January to the end of March 2026.
Figures checked: 22 October 2026
TEST, DEMO and production serve different purposes
KSeF is Poland's national e-invoicing system. The CIRFMF repository describes the KSeF API 2.0 environments: TEST with release candidates, the pre-production DEMO and the production PRD. The documentation warns against sending production invoices and real data to the test environments. It also points out that in TEST the data of different integrators is not isolated under the authentication method it describes. So you prepare fictional data for the trial, and the person responsible knows which environment each call goes to.
| KSeF API test scenario to agree | Expected evidence |
|---|---|
| A valid test document | the link between the local case and the API result |
| A rejected document | a readable reason and where to correct it |
| An interrupted wait for the result | a state that shows what has already been done |
| A retry of the work | no uncontrolled repetition of the operation |
| A wrong permission | a stop and a message to the right person |
- 01EnvironmentTEST or DEMO with fictional data
- 02Casethe document, the permission and the expected result written down before the trial
- 03Runthe case number, the call, the status and the time
- 04Evidencea record that lets you reconstruct the run
- 05Decisionaccepted or to be fixed, with the reason
- The version of the API documentation the trials used
- A description of the environment and the test data
- The result of each trial with its case number
- The list of exceptions that go to accounting
What KSeF automation costs and when it pays back
- Today
- 1,000 invoices × 3 min = 50 h × €34.90 = €1,745
- With the system, a person checks the output in 15% of the time
- €262
- Model, 1 call per case, Claude Sonnet 5.5
- €7
- Cost of one case
- €1.75 today, €0.27 with the system
- Saving
- €1,476 a month
Payback of €3,000
2.0 months
The volume, the time and the checking share are the scenario's assumptions. €34.90 an hour is the EU average hourly labour cost for 2025 according to Eurostat. Model: 2,500 input tokens and 300 output tokens per call at Anthropic's rates, converted at the ECB rate of 1.1205 USD per euro on 22 October 2026.
The count covers the work around a case: searching, reading, writing and passing it on. What stays is the time to check the output, 15% of today's work in the scenario. Before we quote, we measure both times on 20 to 100 cases your team has already handled, in a €0 test that takes 5 working days.
Before you order an integration, compare the cost of the module, its configuration and an extra KSeF flow, as the KSeF automation page counts it. Include acceptance on scenarios and handling exceptions after the start in the budget. According to Poland's Ministry of Finance (2026), the National Tax Information service answered over 70,000 emails about KSeF from January to the end of March 2026.
Test data is part of the preparation
The CIRFMF test data scenarios show how to create test data and permissions, among others for sole traders and VAT groups. That is material for preparing the context of a test. Granting permissions in production is a separate procedure. The details of behaviour depend on the operation and the current API contract, so the table describes trials to agree with the supplier. The message „the API responded” on its own is too vague for accounting to know what to do next.
Your invoicing program supports KSeF
the program's features and their configuration
no build
Work after receiving an invoice stays manual
automation of cost coding and the approval flow
from €3,000
Several systems and your own statuses
an integration with the KSeF API, accepted on scenarios
priced after the review
Where to start
If your program supports KSeF, start with its own features, as our step-by-step integration guide shows. For the call, it is enough to name the system and the task that stays manual despite the existing connection. We build this kind of rollout as part of AI automations. For the free process review, a description of one case from recent weeks and the tools it went through is enough. You do not need to send confidential documents, and you get a written plan within 2 working days.
Worked example · Scenario
How we count the payback: invoices from KSeF
We run the same count for your invoices in the free process review.
€1,396
a month for checking 600 invoices from KSeF by hand
Payback: 2.5 mo.
4 minutes per invoice (a check against the order and the cost description) and checking in 15% of the old time are our assumptions. €34.90 an hour is the EU average hourly labour cost for 2025 according to Eurostat, for companies with 10 or more employees. We measured the model cost of €0.004 per invoice in our invoice coding system, converted at the ECB rate of 1.1205 USD per euro on 22 October 2026.
See the full calculation →
