KSeF (National e-Invoice System) is the state „intermediary” between the invoice issuer and the invoice recipient. Instead of sending PDFs to each other, companies send unified data file (XML). The KSeF gives it a number, confirms delivery and... keeps order.
The result? Fewer errors, fewer emails with attachments, easier automation in accounting.
KSeF - National e-Invoice 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 „only 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 (NIP, date, VAT rate, total) has a specific compartment. The accounting software doesn't „read the picture,” it just immediately takes data from the right places. This is what „structured data”.
It's scheme version This „partitioned” invoice. That is, the form issue number, not the new document type. When you hear FA(3), think: „OK, current data box design.”.
You don't have to „do anything with FA(3)” manually - this support 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 takes on the system itself (KSeF number, delivery path and storage).
Signature/qualified electronic seal is used for login and authorization and granting of rights - and not for signing the invoice file itself.
Briefly
When you base dp KSeF access solely on one person, then rotation or absence of an employee - means downtime.
You can read more about the differences between e-signature and business signature here.
Is the KSeF already working „hard”?
The obligation to issue is postponed: large from 1.02.2026, others from 1.04.2026. Collection from the 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 to login and authorization, not for „docking” to a file.
Will B2C also enter the KSeF?
As of today there is no obligation Issuing invoices to consumers in KSeF (can be done voluntarily).
Is it better to have a „business” signature than a „personal” one?
For access - blank, count 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 will prepare a short checklist on how to make a kit.
