Current information about corporate customer invoicing services.

The BuyerPartyIdentifier element must not be empty

During the autumn of 2024 we will start checking the voluntary BuyerPartyIdentifier element, following the Finvoice Implementation Guidelines, meaning that if this data field is on an invoice it must contain at least six characters. This means that the BuyerPartyIdentifier element must not be empty.

ISO-8859-15 standard

During the autumn of 2024, we will check that the encoding in the content of the e-invoices OP has received follows the ISO-8859-15 standard. It will no longer suffice that the invoice has the correct encoding:<?xml version="1.0" encoding="ISO-8859-15"?>. Instead, the invoice content must truly follow the standard, not UTF-8 for example.


Changes to the E-invoicing Act – As OP’s customer, your e-invoices conform to the new format

The new Finnish E-invoicing Act changed the requirements for business-to-business sales. As of 1 April 2020, businesses and public entities have the right to receive, upon request, e-invoices that conform to the European standard (EN16931) from other companies.

The E-invoicing Act does not apply to businesses whose turnover is less than 10,000 euros and businesses that only trade with consumers. As an OP customer who initiates payments, you can use the online service to send and receive Finvoice 3.0 invoices that conform with the requirements.

Changes to e-invoicing

OP has upgraded its ability to receive electronic invoicing data as of 1 January 2016. As a result of the upgrade, the reception of the oldest types of electronic invoicing material (Finvoice, Finvoice 1.1 and Finvoice 1.2 messages) has now ended. The system is now only able to receive material in compliance with Finvoice 1.3, 2.0 and 2.01 and newer versions.

Any material in compliance with the older versions that arrives after 1 January 2016 will be rejected and an error message will be sent to the customer.

Why can't the old versions still be used?

OP wants to continuously develop the electronic invoicing services provided to its corporate customers. This upgrade is our way to simplify and standardize the processing of Finvoice messages, thereby facilitating rapid and improved customer support. By reducing the number of supported versions, we are able to improve production reliability and efficiency and to decrease vulnerability to errors. The change also enhances the opportunities of our corporate customers to develop their own invoicing services. This will be reflected as even better service for our customers in the future.


The use of a newer version of Finvoice often requires that the invoicing companies contact the payment transfer software provider and electronic invoice operator. We recommend that our corporate customers contact their own software provider and ensure that the current software will support Finvoice 1.3. or a newer version.

Transfer of attachments along with e-invoices

OP has enhanced its corporate e-invoicing service with the possibility to send and receive attachments to e-invoices. The transfer of attachments is possible through the Web Services channel and OP’s Online service for corporate customers and as data transfers through the online services of corporate customers. E-invoices with attachments can be sent and received using Finvoice software that is capable of handling attachments. OP’s Kultalinkki bank connection program contains support for the sending and receiving of attachments.

The processing of attachments complies with the Finvoice 2.01 standard of the Federation of Finnish Financial Services.  The attachment must contain supplementary information to the invoice that is essential for bookkeeping.  The transfer of attachments is not in use in consumer invoicing nor is it permitted to send marketing materials as attachments to e-invoices. One e-invoice can be accompanied by a maximum of 1 MB attachment that contains 1-10 attachment documents.

E-invoice and direct payment cancellation requests

For private customer invoicing, OP has added a function by which the invoicer can request a cancellation of an invoice prior to its due date.  The cancellation request can be used, for example, in a situation in which the invoicing grounds for the e-invoice or direct payment nor longer exist or have been changed, or in a situation in which the invoicer has experienced a production error that affects the invoicing.

The cancellation request is primarily intended to be a service linked to private customer invoicing, but at OP, the cancellation request can also be used for invoices sent to OP’s Online service for corporate customers. Companies that have data transfer capabilities will receive the request as a credit invoice.

The use of the cancellation request is possible for invoicers who have the capability to generate cancellation request messages within their own systems. More detailed information about the specifications of the cancellation requests can be found in the Finvoice 2.01 implementation guidelines published by the Federation of Finnish Financial Services.

Read more about Finvoice at the Finance Finland website