Payment import from Fortnox

Last updated: 6 October 2025

In this article

Opter can be connected to the Fortnox accounting system, www.fortnox.se. Then it is possible to:

When a payment import is made from Fortnox, Fortnox sends the invoice number and the amount paid. If the payment has been made in a currency other than the default currency in the Opter system, Fortnox will also send the current exchange rate at the time of payment.

If you import payments from Fortnox, you must have SEK as the default currency in Opter.

Conditions

Invoice export first

As the invoice numbers to which the payments apply must match between Opter and Fortnox, invoices must first have been exported from Opter to Fortnox in order to be able to import payments. For more information, see Invoice export to Fortnox.

Licences

To be able to connect (integrate) Opter to Fortnox, you need an integration licence. You also need to have software licences for invoicing and accounting in Fortnox. These licences (also called "programs" and "add-ons") can be ordered in the Fortnox program. Contact Fortnox if you need more information about your licences.

We recommend that you first set up the invoice export according to Invoice export to Fortnox, which requires an integration licence and invoicing licence in Fortnox. Next, check whether you have the accounting licence in Fortnox. If you don’t already have it, you’ll need to add it so that you can import payments.

Standard currency

For the export of invoices and supplier bills to Fortnox, and the import of payments from Fortnox to Opter, to work, the default currency in Opter must be Swedish kronor (SEK).

Do not change the default currency as that would cause major problems in the system. If your default currency is not the Swedish krona, you will not be able to export invoices and supplier bills to Fortnox, or import payments from Fortnox.

Currency codes

Fortnox only accepts three-letter currency codes, such as “DKK”, “SEK”, “GBP” and “EUR”.

Exchange rates

It is important that you always use exactly the same exchange rates in Fortnox and Opter, to avoid issues such as exchange rate losses and payments that do not match the invoice in Opter exactly and are therefore recorded as advance payments.

To always have the same exchange rates in Fortnox and Opter, proceed as follows:

  • In Fortnox: Go to Invoicing > Currency, and set Automatic exchange rates to “NO”.

  • Set exactly the same exchange rates in Fortnox and Opter. When updating an exchange rate, change the exchange rate at the same time in both Fortnox and Opter. In Opter, exchange rates are set under Economy > Currencies> Currency rates tab.

Step 1: Create a payment import

To import payments from Fortnox, you must first create the payment import.

  1. Click on Economy > Payment import and then on Read file at the bottom right.

  2. Click on , next to the File format drop-down list.

    The Payment Import window opens.

  3. Create a new payment import by clicking on New in the Payment Import window and giving it a name (for example "Fortnox"). The following fields must be filled in:

    • Import type: FortnoxAPI

    • Import format: API

    • Ignore payments before: Refers to the date the payment was registered in Fortnox. Enter the registration date from which payments will be imported into Opter.

    • Ignore numbers below: Refers to the invoice number in Fortnox. Payments for invoices with lower numbers are not imported into Opter. By default, this field is set to "0", which means that payments for all invoices exported from Opter will be imported.

    Tick Use service account if you wish to use a service account when importing payments. Further information on what a service account is can be found in Invoice export to Fortnox.

    Click on Save to save all changes.

  4. The new file type can be seen in the Payment import - Settings window. Click on Ok to close the window.

Step 2: Importing payments from Fortnox

  1. Click on Economy > Payment import and then on Read file at the bottom right.

  2. Select "Fortnox" (or the name given to the payment import for Fortnox) from the File format drop-down list.

  3. Click on Ok to import the payments.

    If you are not already logged in to Fortnox, a new window will open where you log in with your usual Fortnox username and password. If authentication is successful, the import starts.

    The following applies with regard to payment imports:

    • If the payment was registered before the date specified for Ignore payments before, the payment is not imported.

    • If the payment concerns an invoice with a lower invoice number than the one entered in Ignore numbers below, the payment is not imported.

    • The invoice/OCR numbers must match between Opter and Fortnox, otherwise the payments are not imported.

  4. Click on Save payments in the bottom right-hand corner.

The imported payments are displayed in Economy > Manual payments.

See also