When you log in to MyTax, your tax-related letters will change from paper to electronic form automatically. Read more about the changes.
Declare tax-exempt use for demonstration purposes in MyTax if possible. If you cannot use MyTax, you can use a paper form or authorise another person to act on your behalf.
Choose your filing method
Submit the declaration on this form about one week before you start the demonstration use.
If the Tax Administration does not have your address, for example if you live abroad, also submit the Notification of mailing address.
Download the form
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The online authorisation mandate
You can use the Suomi.fi Authorization to enable you to deal with taxes for another person – including legal persons, companies, other entities – 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 written in the name of a company, to manage a single tax-related issue. If you – either personally or for an organisation that had been authorised – submit tax-related information on paper, a copy of the letter of authorisation has to be enclosed. A letter of authorisation does not provide access to MyTax.
Power of attorney for managing the taxes of a company (3804)
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Page last updated 1/1/2026