When you log in to MyTax, your tax-related letters will change from paper to electronic form automatically. Read more about the changes.
Business operators and self-employed individuals report information on their business activities for income taxation using tax return form 5 in MyTax. Submit the information in MyTax if possible. If you cannot use MyTax you can send a paper form or give out a letter of authorisation to have another person deal with tax reporting for you.
If you are registered as a self-employed individual, you must always file the return even if you have no business activity.
Choose how to submit
Other e-services:
Ilmoitin.fi (website for electronic transfer of files)
If you opt for paper filing, send the enclosure forms with your tax return. You can find the return address on the first page of the form.
Instructions
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The online authorisation mandate
You can use the feature called “Suomi.fi Authorization” to enable you to deal with another person’s taxes through e-services, over the telephone, or by visiting a service point on their behalf.
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Letters of authorisation on paper
You can receive a letter of authorisation from the other person. It will enable you to deal with that person’s taxes on the telephone, by visiting a service point on their behalf, or by submitting information on paper tax forms. To have a letter of authorisation (often called a ‘power of attorney’) does not provide access to MyTax.
Letter of authorisation for tax representation of individual taxpayers (3818)
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When is there no need for an authorisation mandate?
The following circumstances are examples of when you can deal with someone else’s taxes with no authorisation.
You have child younger than 18 and you handle the child’s taxes
You are automatically authorised to access MyTax for the child, without an authorisation. Log in to MyTax and select “Act on behalf of someone else”.
Read more about this subject on Suomi.fi
You are a guardian
You do not need a Suomi.fi authorisation when your continuing power of attorney for being a guardian is officially confirmed, or when you are registered as a private guardian. Log in to MyTax and select “Act on behalf of someone else”.
Note: If you are a public guardian, in other words, a public official employed by a public guardianship office, you can only use paper forms.
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Key terms:
The Tax Administration can use automated decision-making in the context of resolving tax matters. This means that a decision concerning your tax matter may be based on partial or full use of an automated decision-making system. Read more about automated decision-making at the Tax Administration (only in finnish).
Page last updated 11/20/2023