Tax Return – business operators and self-employed persons

Business operators and self-employed persons file their tax return once a year in spring. If you are registered as a self-employed operator you must always file the return. This applies also to times when you have no activity.

The Tax Administration calculates your final income tax based on the information you have submitted in the return. Prepayments that you have made are taken into account in the calculation. In addition to the tax return on your business, you will (each spring) receive a pre-completed tax return for your personal income.

The deadline for filing tax returns for business income is 3 April 2018

The return date may also be 8 May or 15 May 2018.

Check the tax return form for the deadline. Spouses submit their tax returns on the same date as the business operator.

Use e-filing

Send a tax return file from your accounting software (

You need a Katso user ID for filing your tax return in file format or via Tyvi operators. A Katso ID allows you to log in to the e-filing website.

Tyvi service providers can also help you to file your tax return. Some Tyvi services are subject to charge.

You can also print out a paper form and send it to us by post

Extension of time for filing

You may ask for an extension of time for filing the tax return if you have a valid reason for it. The Tax Administration may extend the filing time if you ask for it before your deadline.

Print out the form  (Application for extension of time to submit tax return).


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