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6U Tax return of business activities − foreign corporate entity (3053) Forms

Form 6U is the main tax return form for foreign companies or entities and their Finnish branches. If you believe that you should be treated as having no permanent establishment in Finland, you must file Form 6U with Form 80 enclosed.

Corporations must file their income tax return electronically.

Choose how to submit

Submit the tax return in MyTax.

Go to MyTax

2025 and 2026 – Income tax return − foreign corporate entity, filling instructions

You can submit the information electronically, for example:

You can file on paper only if there is a special reason (for example, if electronic filing is impossible due to technical difficulties). If you file on paper, you need not apply for a special permission, and the Tax Administration does not need to be notified of the reason in advance. The Tax Administration may ask for the reason in connection with tax control.

Send the paper form to:

Finnish Tax Administration
OCR service of corporate taxpayers' returns – Yhteisölomakkeiden optinen lukupalvelu
PO Box 200
FI-00052 VERO
FINLAND

Download the form

Instructions

Attachment forms

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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.

See how to grant and request a Suomi.fi authorisation

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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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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 3/12/2026