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How to fill in Form 6B: the Oy tax return section by section

Karma Accounts · Published 27 October 2026

To fill in Form 6B, you start from the closed books and adjust them for tax: list the shareholders and any loans or payments to them, enter income and expenses (giving both the booked and the tax figure where they differ), enter the balance sheet at tax values, and answer the questions on the audit and ownership changes. For tax year 2026 the company pays 20 % on taxable income. This guide follows the Tax Administration's (Verohallinto) Form 6B for tax year 2026 (paper version VEROH 3052 1.2026), used for financial years ending in 2026 and almost identical to the 2025 form. Check the version for your tax year, as wording can change.

The deadline, attachments and who signs are in our Form 6B deadline and checklist. In short: four months from the end of the financial year's last month, with the financial statements attached.

Where you fill it in

There are three electronic routes:

• MyTax (OmaVero): on the home page, under Corporate income tax, choose File a corporate income tax return for the right tax year. MyTax works out the net assets for you.
• Accounting software: the program builds the return from the books and sends it through the Tax Administration's interface. Many small companies file this way, through their accountant.
• Ilmoitin.fi: upload a file made by software.

Paper is only for when e-filing is not possible, for example because of a technical fault. The questions are the same on every route.

Basic details

Name, business ID, financial year, a contact person, and a few boxes (Åland activity, IFRS, transfer pricing, business transfer or share exchange) that a typical small Oy leaves unticked.

Shareholders, payments and loans

List each shareholder with name, personal identity code or business ID and number of shares, even if the company paid them nothing. For a shareholder that is a company, that is all. For a person, also enter what the company booked during the year, on an accrual basis, to them and to their relatives:

• rent and interest
• transfers, such as assets the company bought from them
• other payments, such as a guarantee fee
• shareholder loans: the amount on the year-end balance sheet

Salaries and dividends do not go here. With more than 10 shareholders, list only those owning at least 10 %; if every shareholder owns under 10 %, no shareholder details are needed, and the paper form has a box to tick for that. But a shareholder or relative who has a shareholder loan is always reported, whatever their holding. What a shareholder loan means for the owner's own tax is a separate matter.

Separate parts cover a company-owned home used by an entrepreneur shareholder or their family, and share issues or share capital changes after the year end. A small Oy without these leaves them empty.

Dividends and other distributions

Fill this in only if a distribution has been decided and the financial statements have been adopted: the decision date, the date from which the dividend can be withdrawn, and the total amount. A distribution from the reserve for invested unrestricted equity (SVOP) has its own row. If nothing is distributed, leave it empty. Who can decide a dividend, and the separate annual return on dividends, are covered in paying dividends.

The income tax calculation: bookkeeping and tax columns

The calculation has two columns, Kirjanpito (the figure in the books) and Verotus (the figure that counts for tax), but most lines take only one figure. Turnover, purchases, staff costs and most other expenses go straight into the tax column. Where the books and tax differ, the form has a pair of lines: the booked amount in the bookkeeping column, and the taxable or deductible portion on the line below, in the tax column. These are the pairs a small Oy usually meets:

Entertainment is the usual difference: half of it is deductible (EVL 8 §). Tax depreciation on machinery is at most 25 % a year of the remaining value, and it can never exceed what has been booked as depreciation in that year or earlier (EVL 54 §). To deduct more than this year's planned depreciation, the company books a depreciation difference (poistoero) or uses earlier booked depreciation left undeducted (form 12A). The temporary 50 % rate ended with tax year 2025. From tax year 2026, membership fees of organisations with labour market aims are not deductible. Group contributions received and given each have one line in the tax column, itemised on form 65.

The result is the business profit (taxable income items less deductible expenses, both from the tax column) or a business loss. Do not enter losses from earlier years. The Tax Administration deducts confirmed losses itself.

What you do report is a change of owner. If more than half of the shares changed owners during the year, or in steps over several years, enter the tax year in the part on ownership changes. For changes in steps, that is the year before or during which losses stopped being deductible. Indirect changes count too: a change of owners in a shareholder that owns at least 20 % of the company. The form asks for this whenever it happens, not only when there are losses.

The net assets calculation (varallisuuslaskelma)

The net assets calculation is still part of Form 6B. You start from the balance sheet, but enter tax values: fixed assets, inventory, financial assets (receivables, cash and bank) and other assets, then liabilities and equity. Assets are generally at their undepreciated acquisition cost for tax. Property and securities have their own valuation rules (forms 18 and 8A). Shareholder loans go under other assets. Debts to shareholders have their own line under liabilities.

Net assets are assets less liabilities. MyTax calculates them. On paper, a negative figure goes in its own box without a minus sign. A deferred tax liability does not count as a liability here.

The figure matters to the owners. The Tax Administration uses the company's net assets to work out the mathematical value of its shares, and dividend tax for the next year depends on that value.

Audit, attachments and corrections

Say whether the accounts were audited: yes, "not yet, done later", or exempt. A small Oy may leave the auditor unelected if, in both the last and the previous financial year, it exceeded at most one of these: a balance sheet total of 100 000 euros, turnover of 200 000 euros, three employees on average. This does not apply if its articles require an auditor, or if its main business is owning and managing securities and it has significant influence over another company. Then attach the financial statements as described in our Form 6B checklist.

You can correct the return until the assessment ends, at the latest 10 months after the end of the financial year's last month. A new return replaces the earlier one completely, so it must contain every figure, not only the changes. You can start from the details you filed before.

A worked example

A one-owner consulting Oy, financial year 1.1.–31.12.2026, no auditor, no earlier losses. The table reconciles books and tax; on the form, lines without a difference are one tax-column figure.

Profit before income tax is 120 000 − 75 000 = 45 000 euros; taxable income is 120 000 − 74 300 = 45 700 euros (45 000 + 600 + 100). The tax is 20 % × 45 700 = 9 140 euros. It goes in the bookkeeping column as income taxes, with no tax-column figure, leaving a profit of 35 860 euros. If the company instead had a confirmed 5 000 euro loss from 2024, you would still not type it in: the Tax Administration deducts it, and the tax becomes 20 % × 40 700 = 8 140 euros.

Net assets: machinery 9 000 + receivables 15 000 + bank 56 000 = 80 000 euros of assets, less 25 000 euros of liabilities (payables 4 000, accruals 11 000, other 10 000) = 55 000 euros. Equity agrees: share capital 2 500 + earlier profits 16 640 + this year's 35 860 = 55 000.

The owner is listed with 100 shares and no loans or payments. If the general meeting on 18.3.2027 decides a 10 000 euro dividend, available from 25.3.2027, those three facts go in the distribution part.

Common mistakes

• Leaving the shareholder part empty because nothing was paid, or leaving out a relative's or small shareholder's loan.
• Entering all the entertainment as deductible.
• Typing in last year's loss.
• Tax depreciation above what has been booked.
• Filing a correction with only the changed lines.

Frequently asked questions

Where do I find the Form 6B filling instructions?

On vero.fi, under the detailed instructions for the business tax return of corporate entities (in Finnish). They cover the 2025 and 2026 returns.

Do I report losses from earlier years on Form 6B?

No. The Tax Administration deducts confirmed losses automatically. You do report it if more than half of the shares have changed owners, directly or indirectly.

What we do

We close the books, prepare the financial statements and file Form 6B for small limited companies, after you have approved the draft. See limited company accounting or request a quote.

Sources

• Tax Administration: Form 6B detailed filling instructions, tax years 2025 and 2026 (in Finnish)
• Tax Administration: Form 6B description and form versions, 3052 (in Finnish)
• Tax Administration: Form 6B 2026, paper version (in Finnish, PDF)
• Tax Administration: tax return of a limited company and cooperative
• Tax Administration: depreciation of a limited company (in Finnish)
• Tax Administration: depreciation in business taxation, detailed guidance 2025 (in Finnish)
• Tax Administration: mathematical value of a share in an unlisted company, 2026 (in Finnish)
• Finlex: Business Income Tax Act 360/1968, 8, 16 and 54 § (in Finnish)
• Finlex: Auditing Act 1141/2015, chapter 2 section 2 (in Finnish)

Please note: this is general information about Finnish rules, not advice for your own situation, and the rules change. Ask us before you act on it.

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