KSeF Invoice Issue Date and Payment Term: When to Count Invoice Delivery From?

For a standard structured invoice received in KSeF by a domestic buyer with a NIP, the invoice receipt date is the day when the KSeF number is assigned. If the contract says payment is due within 7, 14 or 30 days from receipt of the invoice, that date is usually the practical starting point.

KSeF does not itself determine when the payment becomes due. The system helps establish the invoice receipt date, but the payment term still follows from the contract, the invoice content, rules on commercial transactions and the rules for counting time limits.

The greatest risk of error appears when a company mixes up the issue date, XML submission date, KSeF number assignment date and PDF email date. In a simple KSeF flow, the KSeF number date is key, but exceptions must be checked for buyers served outside KSeF, offline modes and unusual contract wording.

If a domestic buyer with a NIP receives an invoice through KSeF, the structured invoice is deemed received on the day its KSeF number is assigned. That means that for a contract clause such as "14 days from receipt of the invoice", the safest first step is to check the KSeF number assignment date.

This does not mean that KSeF itself sets the payment deadline. KSeF identifies the moment of invoice receipt in the system. The contract, invoice and commercial transaction rules decide whether payment is due after 7, 14, 30 or 60 days, or on a specific date stated on the invoice.

When counting a term expressed in days, remember the Civil Code rule: if a specific event starts the term, the day on which that event occurs is not included in the calculation. In practice, the day the KSeF number is assigned is not day one unless a special contract clause or legal rule says otherwise.

In conversations about KSeF it is easy to say that an invoice was "issued" while meaning three different things. For settlements, that is not enough. You need to know when the document was issued, when it was treated as received by the buyer and what payment term the parties agreed for the transaction.

The issue date matters for invoicing itself. The receipt date matters, among other things, for the buyer's invoice workflow and can be the practical starting point for clauses such as "payable from receipt of the invoice". The payment term is a separate layer: it may follow from a contract, order, terms and conditions, invoice or the Act on Counteracting Excessive Delays in Commercial Transactions.

If you want to organize the difference between issuing, sending and accepting an invoice, see the separate guide How long to send an invoice to KSeF?. This article does not repeat the whole submission process; it focuses on the receipt date and payment term.

In the standard case, the seller issues a structured invoice, sends the FA(3) XML to KSeF, the system accepts the document and assigns a KSeF number. If the invoice contains the domestic buyer's NIP, the invoice becomes available to that buyer in KSeF.

The VAT Act and Ministry of Finance materials state that a structured invoice is deemed received through KSeF on the day its KSeF number is assigned. This matters more than simply clicking "send" in the seller's system, because submission can still fail or processing can finish later.

The Ministry's example illustrates the midnight issue well. An invoice was submitted on 1 February 2026 at 23:56, but the KSeF number was assigned on 2 February 2026 at 00:01. For the domestic buyer, the receipt date is 2 February 2026, because that is when the invoice received its KSeF number.

The buyer does not have to manually open the invoice in the system for the receipt date to arise in the standard KSeF flow. This is not like registered mail, where you wait for physical collection. KSeF is based on the invoice becoming available after the system assigns the number.

If the term is expressed in days and starts from an event, that event may be receipt of the invoice in KSeF. The Civil Code provides that in such a calculation the day on which the event occurs is not counted.

Example: the KSeF number was assigned on 2 February 2026, and the contract says payment is due 14 days from receipt of the invoice. Day 1 is 3 February, and day 14 is 16 February. This is a simple example without addressing a situation where the last day falls on a Saturday, a public holiday or another day requiring additional assessment.

In practice, it is worth storing three fields in the system: the KSeF number assignment date, the method used to define the payment term and the calculated payment date. This lets accounting see whether the term follows from a specific invoice date or from a formula such as "X days from receipt".

A PDF visualization of the invoice may be convenient for people: it is easier to read, approve internally or attach to correspondence. It does not change the basic rule for a standard invoice received in KSeF by a domestic taxpayer with a NIP.

If the invoice has been accepted by KSeF and received a KSeF number, a later email with a PDF preview should not be treated as a new receipt date for the structured invoice. Email can help operationally, but it does not replace the KSeF receipt rule.

The same works in the other direction: sending a PDF before the XML is accepted by KSeF does not mean that the standard structured invoice has already been received in KSeF. If you want to separate the PDF from the actual XML, also read Can you send a PDF to KSeF?.

Not every invoice reaches the buyer through standard receipt in KSeF. The VAT Act provides for groups of buyers for whom an invoice may be made available in a way other than through KSeF. In those cases, the receipt date may depend on the buyer's actual receipt of the invoice.

This applies, among other things, when the buyer does not use a Polish NIP in a way that allows the document to be received in KSeF, or when the invoice is made available outside KSeF under the rules for a given recipient group. In that case, you must not automatically apply the simple rule "KSeF number date = receipt date".

For the seller, the most important point is to identify the buyer type before sending a payment demand. The same clause "14 days from receipt of the invoice" may refer in one case to the KSeF number date and in another to the actual date of making the invoice available outside KSeF.

Offline modes do not change the need to first determine how the invoice was effectively received. In offline24, for an ordinary domestic buyer receiving invoices in KSeF, the reference point remains the KSeF number assignment date after the invoice is submitted to the system.

However, if the invoice was made available outside KSeF to a buyer covered by special rules, the actual receipt date may matter. In the failure mode, Ministry of Finance materials also indicate additional rules depending on actual receipt and later KSeF number assignment.

This article does not repeat the full offline mode instructions, because that would distract from the main topic. If you need submission procedures, QR codes, UPO and statuses, go to the guide Sending invoices to KSeF.

In commercial transactions, the payment term is not an arbitrary text field detached from the law. The Act on Counteracting Excessive Delays in Commercial Transactions provides limits, including a 60-day rule for many B2B relationships and shorter terms where the debtor is a public entity, with exceptions listed in the Act.

It is also important that parties to a commercial transaction cannot simply agree that the invoice was delivered on a day other than the actual one. They can, however, precisely describe the payment mechanism, for example "14 days from the date of receipt of the invoice in KSeF" or state a specific payment date on the invoice that is consistent with the contract.

The safest drafting approach is to avoid artificially shifting delivery and instead describe the starting point clearly. For the standard KSeF flow, this may be the KSeF number assignment date. For invoices made available outside KSeF, the actual channel and moment of receipt should be described.

From an accounting perspective, the simplest option is a specific payment date entered on the invoice. The settlement system then does not have to reconstruct a formula, count days and establish what date was the starting point. There is one condition: the date must be consistent with the contract and the rules for the transaction.

The formula "X days from receipt of the invoice" is flexible, but it requires good records. You need to know when the invoice was received in KSeF or when it was actually received outside KSeF. Without that, it is easy to send a payment demand too early or react too late to an overdue receivable.

In practice, many companies will combine both approaches: the contract describes how the term is counted, while the invoicing system already enters a specific payment date. In KSeF, it is worth keeping the KSeF number date with the invoice so that, in a dispute, you can show where the payment date came from.

Before sending a payment demand, do not look only at the invoice issue date. Check whether the document was accepted by KSeF, when the KSeF number was assigned, what issue mode was used and whether the buyer received the invoice in KSeF or outside the system.

UPO is a good operational source of evidence in this process because it links the invoice with system acceptance and the KSeF number. Read more about the confirmation itself in the article UPO in KSeF.

If the payment term is disputed, also check the wording of the contract, order and invoice. KSeF helps establish the invoice receipt date, but it will not answer for you whether the parties agreed on 14 days from receipt, a specific date, prepayment, partial payment or another mechanism.

KSeFGPT can help keep in one place the data that usually drifts between the invoicing system, email inbox and receivables spreadsheet: invoice number, KSeF number, submission status, UPO, buyer data, amounts and payment term.

For a finance team, the key point is not to count deadlines from memory. When the invoice shows the KSeF number, acceptance date and UPO status, it is easier to distinguish a sent document from an accepted one. This reduces the risk of premature payment demands and helps spot invoices without confirmation faster.

KSeFGPT is not a law firm and does not resolve disputes over when a receivable becomes due. It does, however, help collect the data needed for a safer conversation with accounting, a counterparty or an adviser: FA(3) XML, PDF, UPO, KSeF number and document status.

The first mistake is counting the term from the issue date even though the contract refers to receipt of the invoice. In KSeF these dates may differ, especially when the KSeF number is assigned after midnight or the invoice is submitted after offline work.

The second mistake is treating the PDF as the proper invoice. A PDF is a visualization and may help communication, but in the standard KSeF flow the key element is the XML accepted by the system and the KSeF number.

The third mistake is automatically applying one rule to all buyers. A domestic taxpayer with a NIP receiving invoices in KSeF is a different case from a consumer, an entity without a Polish NIP or a foreign counterparty to whom the invoice is made available outside KSeF.

If you want to go deeper without duplicating the whole submission process, start with these four articles:

How long to send an invoice to KSeF? - the difference between issue, submission, acceptance and deadlines for offline modes.

UPO in KSeF - what UPO confirms, when to download it and how to distinguish the KSeF number from the session number.

Sending invoices to KSeF - a broader guide to submission, statuses, authentication and error handling.

Can you send a PDF to KSeF? - why the PDF is a visualization and the actual document in KSeF is the FA(3) XML.