KSeF (National e-Invoice System) is a state-run "intermediary" between invoice issuers and recipients. Instead of sending PDFs to each other, companies send a unified data file (XML). KSeF assigns it a number, confirms delivery and... keeps order.
The result? Fewer errors, fewer emails with attachments, easier automation in accounting.
KSeF - the National e-Invoicing System - is a state-owned platform for issuing, receiving and storing structured invoices (XML in a specific structure). Once an invoice is sent to KSeF, the system assigns it a unique number and stores it as the "sole source of truth." This results in a consistent format, fewer errors and automation of circulation between companies and accounting. It's also part of the broader digitization of VAT accounting in the EU.
Imagine an invoice like a cardboard box with compartments. Each item (TIN, date, VAT rate, total) has a a specific compartment. The accounting program does not "read the picture", but immediately takes data from the right places. This is what is meant by "structured data".
This version of the scheme Of this "partitioned" invoice. That is, the form issue number, not the new document type. When you hear FA(3), think: "OK, the current data box pattern."
You don't have to "do anything with FA(3)" manually - this is handled by the systems (ERP, integrations), it is only important that they are updated.
The obligation enters in stages:
Until these dates, KSeF can be used voluntarily. The key is to prepare the system, people and authorizations so that the launch does not surprise the company.
Important! Invoices for consumers (B2C) remain outside the obligation to issue in KSeF (you can voluntarily), but if you conduct B2B sales - the obligation will cover you according to the thresholds/dates. Foreign entities without a permanent place of business in Poland are excluded from mandatory issuance. (Interpretations)
Don't. In KSeF you don't affix a signature to every invoice. Authenticity and integrity is taken by the system itself (KSeF number, delivery path and storage).
The signature/qualified seal is used for logging in and authorization and granting authorizations - and not for signing the invoice file itself.
Briefly
When you base dp KSeF access solely on one person, then turnover or absence of an employee - means downtime.
You can read more about the differences between e-signatures and business signatures here here.
Is KSeF already working "hard"?
The obligation to exhibit is postponed: large from 1.02.2026, others from 1.04.2026. Receipt from large - from 1.02.2026 for all VAT payers. Until the dates indicated above, you issue invoices as before (paper/PDF/EDI), and you can use KSeF voluntarily.
Do I have to sign every invoice?
No. The signature/stamp is used for login and authorization, not for "docking" to a file.
Will B2C also enter the KSeF?
As of today there is no obligation to invoice consumers in KSeF (you can voluntarily).
Is it better to have a "business" signature than a "personal" one?
For access - no difference, what matters is powers. For order and audit in larger companies -. "business" with company attributes is sometimes more convenient ..
What if the Internet or the system "goes down"?
Then there are two modes available:
Need to select a qualified kit: signature+seal under KSeF? Let us know - at podpisano.pl we do this on a daily basis and we will prepare a short checklist for you on how to make a set.
