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If the company had taxable income, expenses, assets and property, debt or other transactions during the tax year, which affect tax assessment, the company must file an income tax return. The form to complete is Form 6B. It is necessary to do so even if the company or cooperative did not conduct business or other activity during the tax year, or even if the company or cooperative were declared bankcrupt.
Please note that the income tax return must always be submitted if the Tax Administration has sent you a letter instructing you to do so.
If your company has more than one accounting period ending during one calendar year, you must complete a set of tax return forms for each one of the ended accounting periods. The Tax Administration will combine the data from the different periods.
Instructions for the income tax return
On the home page, click File a corporate income tax return under Corporate income tax. Select the appropriate tax year for the return you are submitting.
If your company has more than one accounting period ending during one calendar year, you must complete a set of tax return forms for each one of the ended accounting periods. The Tax Administration will combine the data from the different periods.
Calculation of taxable income
Calculation of net worth
Other additional information
You can inform the Tax Administration of any other matters that have an impact on your company’s or cooperative’s tax assessment here.
Financial statements
Preview and send
Please re-check the details. Select a previous stage or click on Previous to go back and make corrections as necessary. When everything is correct, submit the income tax return.
If you wish to continue filling in the details later, select Save as unfinished. The Tax Administration will not process the tax return before you have clicked on Submit in order to send it. If everything is correct, click Submit.
To find the return you just submitted, open the Communication tab, go to Status of returns and requests and select Filed returns and submitted requests and applications.
After you have clicked on Submit, the status of your return changes to Submitted, and as long as it remains in this state you can still edit it or even choose to delete it. If the return is shown as Received, you can no longer make changes to it.
Besides MyTax, you can send your 6B income tax return and its enclosures electronically in the following ways:
In the same way as for the tax return itself, you should always provide electronic versions of your company’s financial statements (no paper versions), even in cases where the financial statements get ready for sending at a later date, at a time when your tax return has already been completed.
The instructions for completing the return contain a list of the required enclosures. The instructions contain links to further instructions for filling out various enclosure forms, etc. Refer to these instruction when you need to add an enclosure. The final page of the instructions also contains a list of enclosures and many links that provide access to blank enclosure forms and their specific instructions.
Please note that you are only entitled to complete the paper-printed Form 6B with enclosures if your circumstances make it difficult for you to employ the electronic options. An example of such circumstances would be technical problems with our e-file service.
Submit your return within 4 months after the end of the last calendar month of your company’s (or cooperative’s) accounting year.
Illustration: The end date of a limited company’s accounting year is 15 July 2026. Please file the return by 30 November 2026. If 30 November were to fall on a Saturday, Sunday or public holiday, the deadline date would be the next business day.
Please note that if you submit information after the deadline, you may have to pay a late-filing penalty charge or a punitive tax increase. Read more about late-filing charges and the punitive tax increase.
Enclose your company’s financial statement information with the tax return. Check the tax return instructions for company-specific requirements.
If your company has not yet prepared its financial statements by tax-return due date, you can submit more enclosures later. Use e-filing. If you are a user of MyTax and you need to add something to the tax return later, you can do so in MyTax.
Please note that the financial statement must be submitted to the Trade Register even if the company is not operational or does not file a tax return.
You can check the current stage of the processing of your tax return in MyTax. Once you are logged in, you can look up the stage on the front page under Payment status.
If your company has moved on to conduct business in a sector that is different from the sector where it has been active so far, please fill in this information in MyTax (select the Taxpayer details tab). You can inform the Tax Administration of this change immediately, not only at the time when you submit the year’s income tax return.
You are required to indicate the sector of your main business activity in accordance with the Finnish Standard Industrial Classification, TOL 2025. If you are not on MyTax (i.e. submitting Form 6B on paper), please visit the website of Statistics Finland to verify the sector code.
Corporations can pay corporate income tax using the web invoice. A corporate entity whose web invoice address is found in MyTax receives web invoices about prepayments and back taxes, but not about additional prepayments. The web invoice is sent approximately 3 weeks before the due date. Read more about the web invoice.
