Check the KSeF numbers in your payment titles

Klarbon reads your bank statement in the browser and shows, for each transfer, whether its payment title carries a valid KSeF number, a collective identifier, a number with a likely typo, or none. Add your invoices and it matches each payment to them by the gross amount, or in a split payment by the VAT. It is free, needs no account, and nothing is uploaded.

What changes on 1 January 2027?

From 1 January 2027, an active VAT payer who pays a structured invoice to another active VAT payer by transfer, or with another payment instrument that carries a title, gives the invoice's KSeF number in the payment title. When one transfer pays several invoices, it gives a collective identifier instead, which KSeF generates for that set of invoices (Ministry of Finance). The same applies to a third party paying for the buyer, to the issuer when it collects by direct debit, and to the message of a split payment (MPP). The rule is article 108g of the VAT Act, and for split payments the amended article 108a(3)(3) (questions and answers, question 43). Invoices issued in offline mode that have not reached KSeF because of an announced failure need no number.

The bill that defers KSeF penalties passed the Sejm on 6 November 2026 and is before the Senate (Sejm print 3245).

How do I check a statement?

1. Export the statement from your online banking as MT940 or CAMT.053. MT942, CAMT.052 and CAMT.054 work too.
2. Choose the file. Klarbon reads every transfer and its title in your browser.
3. Read the table. Outgoing transfers come first, because a missing number there is your own title; incoming ones follow.
4. Filter by status, then download the table as Excel or CSV, or print it.
5. Add your invoices, if you want the payments matched to them.

What does each status mean?

Polish banks split a title in an MT940 statement into fields of 35 characters (~20 to ~25), so a KSeF number often runs from one field into the next. Klarbon joins them as the payer typed them before it searches. In a split payment message (/VAT/.../IDC/.../INV/.../TXT/...) it reads the VAT amount and says which field holds the number. Payments booked before 1 January 2027 are marked.

How does matching with invoices work?

Give Klarbon the invoices as FA(3) XML files, a ZIP of them, the _metadata.json of a KSeF export, or a list. The KSeF number is not part of the invoice's XML: KSeF assigns it on acceptance and returns it in the UPO (Ministry of Finance). Aplikacja Podatnika names every invoice it downloads after its KSeF number, and puts several in a ZIP (user manual, section 5.3.2), so keep the file names. A list has one invoice a line: the KSeF number, the gross amount and, if you have them, the VAT amount and the seller's NIP, separated by semicolons or tabs.

Each transfer then shows matched, when its amount equals the gross amount, or in a split payment its VAT equals the invoice's VAT; amount differs, with the difference; or not among your invoices. A collective identifier gets a box for the KSeF numbers it covers, which you find in KSeF; once pasted, they are matched like the rest. Under the table, Klarbon lists the invoices with no payment on the statement.

Example (fictional): a transfer of PLN 615.00 titled 1234563218-20270105-1F2E3D4C5B6A-5C, against an invoice of PLN 600.00 with that number, shows "amount differs" by PLN 15.00.

What does it not do?

It reads structured statements only: for a PDF statement, export MT940 or CAMT.053 from your bank. Bank CSV files are not read yet. It does not connect to KSeF, so it cannot decode a collective identifier or confirm that a number belongs to a real invoice. It does not write a payment file; that is planned. It shows what the titles carry and is not tax advice: whether a payment needs a number depends on who pays whom, and how. See also what a KSeF number is and what a collective identifier is.