All of the vehicles that are with foreign registration, but are used to perform official job assignments in Sweden, are required to register into the local road register (vägtrafikregistret). For registering the vehicle with foreign background into the road register, you need a permission from Sweden Transportation Office (Transportstyrelsen). Only exception for not registering the vehicle into the road register is if you are using the vehicle in a short period (maximum 1 month). But even then you need to get the permission from the Transportation Office. To get the permission you need to prove what is the goal of using the vehicle and for how long you plan to do this. To get the permission:

The company or its permanent establishment has to be located in Sweden;

The company has to have adequate activity licenses;

The company has to have good economic indicators. In addition the company has to prove that they have funds of 9000€ per one vehicle and additional 5000€ for each additional vehicle. Authorised auditor or accountant has to confirm the indicators with a separate document.

The company has to have a good reputation.

Before applying for the permission, the company has to have adequate activity licenses. For each vehicle a state fee of 1400 SEK has to be paid to Transportation Office.