National e-Invoicing System (KSeF) number in bank transfers in Poland from 2027 – new requirements for companies
From 1 January 2027, Poland will require a National e-Invoicing System (KSeF) number for certain bank-transfer invoice payments.
In the standard case, the requirement applies when an active VAT taxpayer pays another active VAT taxpayer using an instrument with a payment reference.
For one invoice, the payment will use its KSeF number; for multiple invoices, a KSeF collective identifier will be required.
The recipient’s active VAT status will be determined on the payment date using the Polish VAT taxpayer register.
From 1 January 2027, the KSeF number will also be used in Poland’s split payment mechanism (MPP) transfer instruction.
According to the Polish Ministry of Finance (MF), a foreign entity with neither a registered office nor a fixed establishment in Poland is not subject to this requirement.
The KSeF number must follow the invoice workflow
The identifier should remain linked to the invoice from receipt through posting, approval and payment preparation.
Batch payments require two-way identifier handling
Businesses should be able to generate collective identifiers and decode them when allocating incoming payments.
KSeF payment readiness involves several teams
Accounting, finance, IT and ERP owners all have roles in maintaining the KSeF number throughout the payment process.
Testing should cover the full invoice-to-bank flow
Before 1 January 2027, businesses should test how the KSeF number moves from invoice receipt through to the bank.
From 1 January 2027, a number assigned by Poland’s National e-Invoicing System (KSeF) will be mandatory in bank transfers for certain payments relating to invoices covered by KSeF. The requirement will primarily apply where an active VAT taxpayer pays another active VAT taxpayer by bank transfer or another payment instrument that allows a payment reference to be entered.
For a payment covering one invoice, the invoice’s KSeF number will be entered. For a payment covering more than one invoice, a collective identifier assigned by KSeF will be used. The new rules will also apply to the split payment mechanism (MPP).
For larger organisations, the main challenge will not be completing an additional payment field. It will be ensuring that the KSeF number moves correctly through the entire process: from invoice receipt, through posting and approval, to payment generation. This also matters where accounting services in Poland are outsourced, as the KSeF number must flow correctly between systems and the people involved in processing the invoice and payment.
In this article:
From when will the KSeF number be mandatory in bank transfers in Poland?
The new rules will apply to payments made from 1 January 2027. Until the end of 2026, the requirement under Article 108g of the Polish VAT Act remains deferred.
This date follows from the Act of 5 August 2025, which postponed the application of Article 108g and the corresponding changes concerning MPP to payments made from the beginning of 2027. Businesses should therefore use the remaining part of 2026 not only to adapt systems technically, but above all to test the real data flow between the invoice and the payment.
Who must include a KSeF number in a bank transfer in Poland?
The requirement does not apply to every business or every bank transfer. Under Article 108g of the Polish VAT Act, the standard case concerns a buyer registered as an active VAT taxpayer who pays certain invoices to another active VAT taxpayer using a payment instrument that allows a payment reference to be entered.
In the standard case, the requirement applies when:
- the buyer making the payment is registered as an active VAT taxpayer,
- the payment recipient is registered as an active VAT taxpayer,
- the payment relates to an invoice within the scope of Article 108g,
- a bank transfer or another instrument allowing a payment reference to be entered is used.
The requirement may also apply to a taxpayer other than the buyer if that taxpayer pays an invoice issued to the buyer.
The recipient’s status as an active VAT taxpayer is determined as at the payment date, based on the VAT taxpayer register referred to in Article 96b of the Polish VAT Act. The requirement may also apply to a taxpayer other than the buyer if that taxpayer pays an invoice issued to the buyer. For direct debits, however, Article 108g places the relevant obligation on the invoice issuer.
This does not mean that every third party transferring funds in connection with an invoice automatically falls within Article 108g. The legal basis and nature of the specific payment may also be relevant.
Will every invoice payment require a KSeF number in Poland?
No. The fact that an invoice has been issued through KSeF does not automatically mean that every related transfer must be marked with a KSeF number. Relevant factors include the status of the parties, the type of document and the payment method.
| Situation | Payment reference from 1 January 2027 | Key point |
|---|---|---|
| Payment for one invoice covered by Article 108g | KSeF number | This is the number assigned by KSeF, not the seller’s commercial invoice number |
| One transfer covering more than one invoice | KSeF collective identifier | Allows one payment to be linked to multiple invoices |
| MPP payment for one structured invoice | KSeF number | The number is entered in the MPP transfer instruction |
| Batch MPP payment for structured e-invoices | KSeF collective identifier | Replaces the reference used for batch payments under the previous rules |
| Payment instrument that does not allow a payment reference to be entered | No requirement under Article 108g | Article 108g applies to instruments that allow a payment reference to be entered |
| Certain offline invoice not submitted to KSeF due to an officially announced outage | Exception from the requirement | Follows from Article 108g(4) of the Polish VAT Act |
Poland’s national e-invoicing system (KSeF) · New rules from 1 January 2027
Which KSeF reference should you use from 1 January 2027?
Not every transfer linked to a structured invoice needs a KSeF reference. Whether a reference is required depends on the parties’ VAT status, the invoice type and the payment method.
Situation
Payment reference
Payment for one invoice covered by Article 108g
The number assigned by KSeF, not the seller’s invoice number
KSeF number
One transfer covering at least two structured invoices from the same seller
Links one payment to multiple invoices
KSeF collective identifier
Split payment (MPP) for one structured invoice
The number goes in the split payment (MPP) instruction
KSeF number
Batch split payment (MPP) for structured e-invoices
Replaces the reference used for batch payments
KSeF collective identifier
Payment instrument without a payment reference field
Article 108g applies only to instruments allowing a reference
No Article 108g requirement
Remember
A KSeF number is not the seller’s invoice number. A document may be numbered FV/01/2027/125, while KSeF assigns a separate, unique number of its own.
Must a third party paying an amount corresponding to an invoice always provide the KSeF number?
No. The fact that the transfer amount corresponds to a structured invoice does not necessarily mean that the transfer is a payment for that invoice within the meaning of Article 108g. The legal nature of the payment also matters.
This is illustrated by an individual tax ruling issued by the Director of National Revenue Information (KIS) on 27 July 2026, reference no. 0114-KDIP4-3.4012.366.2026.1.DS, concerning an insurer financing the settlement of claims. In the case described, the insurer was not the buyer of the goods or services shown on the invoice. It transferred funds in performance of its indemnity obligation under an insurance contract. The Director of KIS concluded that, in this model, the insurer was not paying a structured invoice within the meaning of Article 108g and was not required to include the KSeF number in the payment instruction.
The ruling is relevant beyond the insurance sector because it highlights an issue that may arise in more complex settlement models: it is not enough to identify who technically executes the transfer. Businesses must also assess the legal basis on which the funds are being transferred.
This does not create a general exemption for all payments made by insurers or other third parties. It is an individual tax ruling issued for a specific future event, so its conclusions should not automatically be applied to other payment models.
What is the difference between a KSeF number and an invoice number?
A KSeF number is not the invoice number assigned by the seller. For example, a document may have the internal number FV/01/2027/125. Once the e-invoice is accepted by KSeF, the system automatically assigns a separate, unique identification number.
The Ministry of Finance states explicitly that the KSeF number and the invoice number referred to in Article 106e(1)(2) of the Polish VAT Act are two different numbers. The KSeF number is also not part of the invoice XML file itself.
This distinction has practical implications for businesses using ERP systems. If the system stores and passes only the internal invoice number to the payment module, correctly retrieving the document from KSeF will not, by itself, be sufficient to automate payments from 2027.
What is a KSeF collective identifier for bank transfers?
A KSeF collective identifier allows a payment covering multiple invoices to be marked with a single identifier. It is assigned to at least two structured invoices issued by the same seller. To generate it, a list of the invoices’ KSeF numbers must be provided. This can be done, among others, by an issuer or recipient with the appropriate authorisation. The functionality will be available both in solutions provided by the Ministry of Finance and in commercial finance and accounting systems connected to the KSeF API.
The ability to decode a collective identifier will also be important. KSeF will allow users to check which KSeF numbers are covered by that identifier. Businesses should therefore prepare two processes:
- generating collective identifiers for outgoing payments,
- decoding them for customer payments received and allocating receipts to the correct receivables.
The second process can easily be overlooked if a KSeF implementation project is analysed only from the accounts payable perspective.
How will the KSeF number work with Poland’s split payment mechanism?
From 1 January 2027, the KSeF number will also be used in the transfer instruction under the split payment mechanism (MPP). For a single e-invoice, the taxpayer will enter its KSeF number. For a batch payment covering structured invoices, the collective identifier assigned by KSeF will be used.
Businesses using MPP should therefore test not only standard bank transfers, but also the creation of split payment transfer instructions and batch payments.
Where is the biggest KSeF payment risk in Poland? Between the invoice and the bank transfer
In a small business, the KSeF number can still be checked manually. With hundreds or thousands of invoices each month, however, manually searching for identifiers and transferring them into payment data becomes inefficient and increases the risk of error. The key question is therefore not: where do we enter the KSeF number? The more important question is: does the KSeF number remain linked to the liability throughout the finance and accounting process?
The data flow may look as follows:
KSeF → document workflow system → ERP / accounting system → approval → accounts payable → payment batch → bank.
Poland’s national e-invoicing system (KSeF) · Payments from 1 January 2027
The KSeF number must stay linked from invoice to bank transfer
From 1 January 2027, certain payments covered by Polish VAT rules must include a KSeF number or KSeF collective identifier. The challenge is keeping the correct identifier linked to the invoice all the way to the bank.
KSeF
The accepted e-invoice receives its own unique KSeF number, separate from the seller’s invoice number.
Document workflow system
The identifier remains linked to the invoice as it moves through the document workflow.
ERP / accounting system
The KSeF number is stored with the invoice and remains linked to it after posting.
Approval
The identifier follows the approved document into payment preparation.
Accounts payable
The KSeF number or collective identifier is included in the data used to prepare the payment.
Payment batch
One invoice: KSeF number. At least two structured invoices from the same seller: KSeF collective identifier.
Bank
The identifier is entered as the payment reference in the bank transfer or split payment mechanism (MPP) instruction.
The biggest KSeF payment risk sits between the invoice and the bank transfer. If the identifier becomes detached at any stage, it must be found and re-keyed by hand.
If the identifier becomes detached from the invoice at any stage, the problem may only become visible when the payment is being prepared. An employee will then need to locate the KSeF number again and manually assign it to the correct payment.
Preparation for 2027 should therefore focus on data continuity from invoice to payment, not only on configuring an additional field in online banking.
What should accounting, finance and IT teams check before 2027?
Preparing for the new rules should not be treated as an accounting-only task. The KSeF number must be transferred correctly throughout the process, from receipt of the invoice to execution of the payment.
Accounting should confirm that the KSeF number is stored with the invoice and remains linked to it after posting.
Finance should verify that the KSeF number or collective identifier is automatically included in the data used to prepare the payment.
IT or the ERP system administrator should check that data is transferred correctly between KSeF, the accounting system, the document workflow system and online banking.
The CFO or chief accountant should define how non-standard scenarios will be handled, such as batch payments, payments made by third parties or changes in a counterparty’s VAT status.
In practice, the objective is not simply to add a KSeF number to a bank transfer, but to ensure that the correct identifier reaches the correct payment without manual searching or re-keying of data.
For businesses that outsource accounting, it is also worth establishing how KSeF data will be exchanged between the company and its accounting provider. As part of its accounting services in Poland, getsix® can support businesses in organising accounting processes and settlements relating to invoices handled through KSeF.
How should a business prepare for the mandatory KSeF number in bank transfers?
The best test is not to check a single banking field, but to trace a real invoice from receipt through to payment.
- Select invoices retrieved from KSeF and check where their KSeF numbers are stored in the system.
- Trace the number through the entire document workflow – account assignment, approval, posting and settlement.
- Check the payment batch – does the KSeF number flow automatically into the data sent to the bank?
- Test a batch payment and the process for generating the appropriate collective identifier.
- Check incoming payments – can the system decode a collective identifier and allocate the receipt to the correct receivables?
- Define exceptions and responsibilities – who decides what to do when a payment does not match the standard scenario?
This type of test can reveal gaps that are not visible when only the integration between the accounting software and KSeF is tested.
Must a foreign VAT taxpayer include a KSeF number when making a payment in Poland?
According to the current position of the Polish Ministry of Finance, a foreign entity making a payment to a Polish taxpayer for a structured invoice is not required to provide a KSeF number or collective identifier if it has neither a registered office nor a fixed establishment in Poland.
This is particularly important for international groups and businesses using centralised payment processes. Registration of a foreign entity as an active VAT taxpayer in Poland should therefore not, by itself, lead to the assumption that every payment made by that entity will have to carry a KSeF number.
For more complex models – for example, central settlement of liabilities by a foreign company, payments made by another group entity or the use of foreign bank accounts – the specific payment model should be reviewed before the procedure is implemented.
What should businesses remember about KSeF payment references from 2027?
From 1 January 2027, a KSeF number or collective identifier will become a mandatory element of certain payments relating to invoices covered by KSeF. This does not mean, however, that every transfer connected with a structured invoice must carry such a reference. Before making a payment, businesses need to consider, among other things, the VAT status of the parties, the type of invoice, the payment method and – for more complex structures – the legal nature of the transfer.
For larger organisations, the key task is to ensure that the KSeF number is preserved throughout the process from invoice to bank. Before 1 January 2027, businesses should therefore test the real document workflow, batch payment handling and the allocation of incoming payments marked with a collective identifier.
Checking whether invoice posting and settlement processes are ready for the KSeF requirements from 2027 may require both document workflows and responsibilities across accounting and finance to be organised. getsix® can support businesses in this area through its accounting services for businesses in Poland.
Sources and legal basis:
- Act of 11 March 2004 on Tax on Goods and Services.
- Act of 5 August 2025 amending the Act on Tax on Goods and Services and the Act amending the Act on Tax on Goods and Services and certain other acts, Journal of Laws 2025, item 1203.
- Polish Ministry of Finance – KSeF number and collective identifier.
- Individual tax ruling issued by the Director of National Revenue Information (KIS) on 27 July 2026, ref. 0114-KDIP4-3.4012.366.2026.1.DS.
This article was written by the getsix® Editorial Teamgetsix® provides accounting, tax advisory, HR and payroll, and business consulting services, supporting companies operating in Poland. The getsix® Editorial Team prepares practical information that makes Polish accounting, tax, and HR and payroll matters easier to understand.
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