Who paid you? Check payments by KSeF number in 2 minutes.

Q: How do you check the number?

A KSeF number has 35 characters (NIP-YYYYMMDD-12 HEX characters-checksum). The last two characters are a CRC-8 checksum of the first 32. If it does not match, the number has a typo and the payment cannot be reliably assigned to an invoice.

Drop in a bank statement (MT940, CAMT.053 or CSV). You will see which payments carry a KSeF number or a collective identifier (IZ) with a valid checksum in the title, and which do not.

Drop the statement file here or click to choose it

MT940 (.sta, .mt940, .txt), CAMT.053 (.xml), bank CSV

Optional: add your sales invoices and we will match payments to invoices by KSeF number and invoice number.

XML files downloaded from KSeF (FA (3)) or a CSV export from your invoicing tool (columns: number, gross amount, buyer, optionally KSeF number).

🔒 The file stays on your computer. The page has no network access, so nothing is sent. Works offline.

Result

0%of payments ready for 2027

0incoming payments

0with a KSeF number

0with a collective identifier

0with a bad checksum

0without an identifier

0with an invoice number only

0payments matched to invoices

Date	Amount	Counterparty	Status	Found	Invoice	Title

Invoices: who paid?

Number	Buyer	Gross	Paid	Status

Search for a KSeF number, IZ, invoice number or transfer title

What changes on 1 January 2027?

For transfers between active VAT payers in Poland, the payer puts the invoice's KSeF number in the transfer title, and when paying several invoices from one seller with a single transfer, the collective identifier (IZ). This also applies to the split payment mechanism. Details (in Polish): ksef.podatki.gov.pl.

The obligation does not cover, among others, payments from consumers, by card, BLIK or cash, or VAT-exempt businesses.

Questions

How do you check the number?

A KSeF number has 35 characters (NIP-YYYYMMDD-12 HEX characters-checksum). The last two characters are a CRC-8 checksum of the first 32. If it does not match, the number has a typo and the payment cannot be reliably assigned to an invoice.

My bank splits the title over several lines. Is that a problem?

No. We join the title fields from the statement and also look for the number with spaces and line breaks removed.

Why do some payments show “no identifier”?

Before 2027 the KSeF number in the title is optional. Such payments have to be matched another way: by invoice number, amount and counterparty.

Do you need a KSeF token?

No. This page only reads the files (statements and invoices) you choose yourself.