Part of
System integrations and APIs

KSeF wired into the flow you already run

Sending an invoice to KSeF is rarely the problem.

The problem is what happens when a document is rejected, when the service is unavailable, and when invoices are produced in three places at once.

Who it's for
3

Who this is for

  • Companies issuing invoices from their own sales system or ERP
  • Shops and wholesalers generating documents across several channels
  • Organisations whose software vendor provides no integration
Scope
4

What it covers

Authentication and permissions

Establishing and maintaining access, managing tokens and permissions for people and for systems.

More

This is where a hastily built integration most often falls over.

Issuing and pre-submission validation

Checking the document structure on your side before it reaches KSeF.

More

A rejection caught locally costs seconds; caught afterwards it costs a correction and a call to the customer.

Rejections and retries

A queue with automatic retries, a clear document status, and a place where accounting can see what is stuck and why.

Receipts, archiving and the fallback mode

Retrieving and storing the official confirmation of receipt, and handling the case where the service is down.

More

The fallback mode is not a theoretical requirement — it is a procedure you have to have ready.

In depth
In depth

Why this isn't "just sending an XML"

Because integrating with a public system is mostly about handling its unavailability and its refusals. Sending a document in the happy path is the smallest part of the work, and the most common reason such a project is underestimated.

What we leave behind

Documentation of the fallback procedure and tests you can run after any change to your sales system. With a statutory obligation that isn't an extra — it is the only way a change elsewhere doesn't switch invoicing off.

Questions
3

Questions about this scope

Our software vendor says they'll add KSeF. Do we need you?

If they add it and handle rejections, receipts and the fallback mode — no. It is worth asking them about exactly those three things: they are what separates an integration that works from one that works until the first error.

We issue invoices in several systems. Is that a problem?

It is the main cost driver in these rollouts. Every document source needs a consistent numbering scheme and a shared KSeF status, otherwise accounting gets three versions of the truth instead of one.

How long does it take?

With one document source and an available API — usually a few weeks including testing against the sandbox. With several sources the workshop sets the scope, because the document flow starts to dominate over the integration itself.

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